bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breeding and Cereal Yield Progress
Authors: Fischer R. A. (Tony) , Edmeades Gregory O. 
Published: March 2010

ABSTRACTThis paper reviews recent progress in wheat (Triticum aestivum L.), rice (Oryza sativa L.), and maize (Zea mays L.) yields resulting from substantial breeding efforts in mostly favorable environments and examines its physiological basis. Breeding and improved agronomy lift potential yield (PY), namely yield with the best variety and management in the absence of manageable abiotic and biotic stresses, and PY increase is a key component of progress in farm yield (FY), the other component being closure of the PY to FY gap. Changes in PY and FY are reviewed for several key production regions, namely the United Kingdom and the Yaqui Valley of Mexico for wheat, Japan and Central Luzon in the Philippines for rice, and Iowa and briefly sub‐Saharan Africa for maize. The PY growth rates have fallen and are currently generally no more than 1% per annum and usually much less. The trajectory of FY with time often closely parallels PY, but, especially in developing countries, there remain large yield gaps. In at least one instance (maize in Iowa) the gap between PY and FY appears to be closing rapidly. Current genetic progress is linked to increased biomass accumulation, and this will remain the way forward in the future given the limits to increased harvest index (HI). There is evidence that recent progress is related to increased photosynthesis (e.g., greater radiation use efficiency (RUE) at the canopy level and/or maximum photosynthetic rate Pmax at saturating irradiance at the leaf level) before and around anthesis. There is no theoretical reason why this trend cannot continue, especially given the vast genetic resources already found within each crop species. However, it will not be easily or cheaply accomplished, so prospects for higher rates of potential yield growth appear to be limited, notwithstanding new molecular tools and claims to the contrary. Closing the yield gap, therefore, becomes more important. Many factors are involved, but breeding can also help farmers achieve this through, for example, improved host plant resistance.
Should Enhanced Resilience Be an Objective of Natural Resource Management Research for Developing Countries?
Authors: Walker Brian , Sayer Jeff , Andrew Neil L. , Campbell Bruce 
Published: March 2010

ABSTRACTProductivity enhancement has traditionally been the main focus of agricultural research to alleviate poverty and enhance food security of poor farmers in the developing world. Recently, the harmful impact of climate change, economic volatility, and other external shocks on poor farmers has led to concern that resilience should feature alongside productivity as a major objective of research. The applicability of recent work on resilient social–ecological systems to the problems of poor farmers is reviewed, and proposals are made for issues that need to be addressed in determining when and how enhanced resilience might become an objective of research.
Learning to Love the Bomb: Robert Lowell's Pathological Poetics
Authors: Beardsworth Adam 
Published: March 2010

Abstract:This paper repositions Robert Lowell's confessional poetry as a form of resistance in Cold War America. It argues that in several of Lowell's key poems the figurative absence at the hypo-centre of atomic culture finds its symbolic equivalent in the depressive trying to recover a lost core of selfhood.
Transcriptional Repressor BCL6 Controls Th17 Responses by Controlling Gene Expression in Both T Cells and Macrophages
Authors: Mondal Arpita , Sawant Deepali , Dent Alexander L. 
Published: March 2010

Abstract
The transcriptional repressor protein BCL6 regulates T cell differentiation by repressing Th2 responses and promoting follicular Th cell responses. However, little is known about the role of BCL6 in Th17 responses. We found that memory T cells from BCL6-deficient mice had increased IL-17 production. Additionally, BCL6 expression is upregulated in CD4 T cells cultured under Th17 conditions. T cells from BCL6-deficient mice showed defective Th17 differentiation and enhanced IL-4 production in vitro; however, normal Th17 differentiation was obtained with BCL6-deficient T cells under culture conditions when highly pure naive CD4 T cells were used, when IL-4 production was inhibited, or when TGF-β levels were increased. Retrovirus-mediated expression of BCL6 in CD4 T cells repressed IL-4 and augmented basal IL-17 mRNA expression. These data support the idea that BCL6 promotes Th17 differentiation through suppression of Th2 differentiation. BCL6-deficient T cells transplanted into Rag1−/− mice produced wild-type levels of IL-17, indicating that, in vivo, BCL6-deficient T cells develop relatively normal Th17 responses. Macrophages from BCL6-deficient mice showed strikingly increased expression of the Th17-promoting cytokines IL-6, IL-23, and TGF-β, and conditioned media from BCL6-deficient macrophages promoted augmented IL-17 expression by T cells. We propose that the increased Th17 activity in BCL6-deficient mice is due, in part, to BCL6-deficient macrophages promoting increased Th17 differentiation in vivo. T cells may require BCL6 for optimal Th17 differentiation; however, BCL6 function in macrophages critically regulates Th17 differentiation in vivo. We hypothesize that increased Th17 differentiation aggravates the severe Th2-type inflammatory disease in BCL6-deficient mice.
CD8 T Cells Activated in Distinct Lymphoid Organs Differentially Express Adhesion Proteins and Coexpress Multiple Chemokine Receptors
Authors: Ferguson Andrew R. , Engelhard Victor H. 
Published: March 2010

Abstract
Previous work from this laboratory showed that generation of memory CD8 T cells by different immunization routes correlates with control of tumors growing in distinct sites. We hypothesized that effector CD8 T cell expression of adhesion proteins and chemokine receptors would be influenced by activation in different secondary lymphoid organs. In this report, CD8 T cells were activated by immunization with bone marrow-derived dendritic cells via i.p., i.v., or s.c. routes. Three distinct populations of activated CD8 T cells arise in mesenteric, axillary/brachial, and mediastinal lymph nodes and spleen based on differential expression of α4β7 integrin, E-selectin ligand, and α4β1 integrin, respectively. In contrast, three subsets of CD8 T cells defined by differential expression of P-selectin ligand and chemokine receptors were induced irrespective of activation site. The majority of activated CD8 T cells expressed CXCR3, with one subset additionally expressing P-selectin ligand, and another subset additionally expressing CCR3, CCR4, CCR5, CCR6, and CCR9. In the mesenteric lymph node, a fourth subset expressed CCR9 and CXCR3 in the absence of CCR5. Similar homing receptor profiles were induced in the same sites after localized vaccinia immunization. Homing receptor expression on CD8 T cells activated in vitro was distinct, revealing influences of both dendritic cells and the lymphoid microenvironment. Collectively, these results identify previously undescribed populations of activated CD8 T cells based on adhesion protein expression and coexpression of chemokine receptors that arise after activation in distinct secondary lymphoid organs.
Fundamental Principles of Quantum Dots
Authors: Parak Wolfgang J. , Manna Liberato , Nann Thomas 
Published: March 2010

AbstractQuantum dots are intermediates between atoms/molecules and bulk material. Therefore they can be described either by upscaling the concepts of atoms/molecules or by downscaling the concepts of bulk materials. This allows for understanding size‐dependent properties, as in particular the size‐dependent wavelength of fluorescence.
Organocatalytic Asymmetric Michael Addition of Pyrazolin‐5‐ones to Nitroolefins with Bifunctional Thiourea: Stereocontrolled Construction of Contiguous Quaternary and Tertiary Stereocenters
Authors: Liao Yu‐Hua , Chen Wen‐Bing , Wu Zhi‐Jun , Du Xi‐Lin , Cun Lin‐Feng , Zhang Xiao‐Mei , Yuan Wei‐Cheng 
Published: March 2010

AbstractThe first organocatalytic diastereo‐ and enantioselective Michael addition reaction of 4‐substituted‐pyrazolin‐5‐ones to nitroolefins has been developed with a chiral bifunctional thiourea as organocatalyst. A wide variety of desired multi‐substituted pyrazolin‐5‐one derivatives with contiguous quaternary and tertiary stereocenters are smoothly obtained in very good yields (up to 98%) with excellent enantioselectivities (up to>99%ee) and acceptable diastereoselectivities (up to 80:20). This experimentally simple process facilitates the access to various enantioenriched, multiply substituted pyrazolin‐5‐one derivatives, potential biologically active molecules, starting from readily available starting materials.
Inhibitors of Human Histone Deacetylase: Synthesis and Enzyme Assay of Hydroxamates with Piperazine Linker
Authors: Chakrabarty Shubhashis , Jasmine  , Bhadaliya Chetan , Nayan Sinha Barij , Mahesh Aruna , Bai He , Blond Sylvie Y. , Jayaprakash Venkatesan 
Published: March 2010

AbstractThe histone deacetylase (HDAC) enzyme plays an important role in gene transcription. Inhibitors of histone deacetylases induce cell differentiation and suppress cell proliferation in tumor cells. Hydroxamates with rigid linker have displayed better inhibition profiles than those with linear and flexible aliphatic linkers. We have designed and synthesized several potential histone deacetylase inhibitors with a piperazine moiety in the linker region to test the effect of reduced linker flexibility. Inhibitors were evaluated for their inhibitory action on human HDAC3/NCoR2 and HDAC8. N‐Hydroxycarboxamide derivatives (compounds 4a–d) were found to be better than N‐hydroxyacetamide derivatives (compounds 6a–d) against HDAC8. Amongst the synthesized compounds, 4a (HDAC8, IC50: 3.15 μM) with no substitution in the aryl cap was the most active and promising lead for further investigations.
Building artificial cells and protocell models: Experimental approaches with lipid vesicles
Authors: Walde Peter 
Published: March 2010

AbstractLipid vesicles are often used as compartment structures for preparing cell‐like systems and models of protocells, the hypothetical precursor structures of the first cells at the origin of life. Although the various artificially made vesicle systems are already remarkably complex, they are still very different from and much simpler than any known living cell. Nevertheless, the preparation and study of the structure and the dynamics of functionalized vesicle systems may contribute to a better understanding of biological cells, in particular of the essential features of a living cell that are not found in the non‐living form of matter. The study of protocell models may possibly lead to a better understanding of the origin of the first cells. To avoid misunderstanding in this field of research, it would be useful if generally accepted definitions of terms like “artificial cells,” “synthetic cells,” “minimal cells,” “protocells,” and “primitive cells” exist. Editor's suggested further reading in BioEssaysSynthetic cells and organelles: compartmentalization strategiesAbstract
Xenobiology: A new form of life as the ultimate biosafety tool
Authors: Schmidt Markus 
Published: March 2010

AbstractSynthetic biologists try to engineer useful biological systems that do not exist in nature. One of their goals is to design an orthogonal chromosome different from DNA and RNA, termed XNA for xeno nucleic acids. XNA exhibits a variety of structural chemical changes relative to its natural counterparts. These changes make this novel information‐storing biopolymer “invisible” to natural biological systems. The lack of cognition to the natural world, however, is seen as an opportunity to implement a genetic firewall that impedes exchange of genetic information with the natural world, which means it could be the ultimate biosafety tool. Here I discuss, why it is necessary to go ahead designing xenobiological systems like XNA and its XNA binding proteins; what the biosafety specifications should look like for this genetic enclave; which steps should be carried out to boot up the first XNA life form; and what it means for the society at large.
Nickel(II) Nitrate vs. Acetate: Influence of the Precursor on the Structure and Reducibility of Ni/MCM‐41 and Ni/Al‐MCM‐41 Catalysts
Authors: Marceau Eric , Che Michel , Čejka Jiří , Zukal Arnošt 
Published: March 2010

AbstractNickel(II) nitrate is the nickel precursor generally selected to prepare oxide‐supported catalysts, due to its low cost, high solubility in water and decomposition at moderate temperatures. However, its decomposition produces NOx, and it is known to melt and redistribute over the support upon heating, leading to poorly dispersed metal particles after reduction and to their partial expulsion from the porous support system. The benefits of using NiII acetate as an alternative to NiII nitrate are explored by investigating a series of model Ni catalysts (1–5 wt %) prepared from the mesoporous siliceous supports MCM‐41 and Al‐MCM‐41. The problems encountered with NiII nitrate, in terms of particle size and redistribution of nickel, are not observed with NiII acetate. In the case of MCM‐41‐supported systems, metal particles are well dispersed and remain located within the porous support. The higher pH of the impregnation solution, favoring electrostatic interactions between nickel ions and the support, may account for the higher metal dispersion. The formation of silicate‐like species in strong interaction with the support does not appear prominent on siliceous MCM‐41 when nickel acetate is the precursor, but seems to be enhanced for higher Ni contents. Finally, Al‐MCM‐41 supports are more sensitive to the exposure to nickel acetate than their siliceous analogues because acetate ions are able to extract Al ions from the support, resulting in a partial disruption of the support organization and to the formation of nickel silicate species.
Theoretical Characterization of Charge Transport in One‐Dimensional Collinear Arrays of Organic Conjugated Molecules
Authors: Viani Lucas , Olivier Yoann , Athanasopoulos Stavros , da Silva Filho Demetrio A. , Hulliger Jürg , Brédas Jean‐Luc , Gierschner Johannes , Cornil Jérôme 
Published: March 2010

AbstractA great deal of interest has recently focused on host–guest systems consisting of one‐dimensional collinear arrays of conjugated molecules encapsulated in the channels of organic or inorganic matrices. Such architectures allow for controlled charge and energy migration processes between the interacting guest molecules and are thus attractive in the field of organic electronics. In this context, we characterize here at a quantum‐chemical level the molecular parameters governing charge transport in the hopping regime in 1D arrays built with different types of molecules. We investigate the influence of several parameters (such as the symmetry of the molecule, the presence of terminal substituents, and the molecular size) and define on that basis the molecular features required to maximize the charge carrier mobility within the channels. In particular, we demonstrate that a strong localization of the molecular orbitals in push–pull compounds is generally detrimental to the charge transport properties.
Multiferroic Domain Boundaries as Active Memory Devices: Trajectories Towards Domain Boundary Engineering
Authors: Salje Ekhard K. H. 
Published: March 2010

AbstractTwin boundaries in ferroelastics and curved interfaces between crystalline and amorphous zircon can, in principle, act as multiferroic structural elements and lead the way to the discovery of novel multiferroic devices which are based on structurally heterogeneous materials. While this paradigm has not yet been explored in full, this review shows that physical and chemical properties can vary dramatically inside twin boundaries and interfaces. Properties that have been already been explored include electric dipoles in a non‐polar matrix, the appearance of superconductivity in twin boundaries and the catalytic reaction of hydrous species in interfaces of radiation damaged material. Some of the fundamental physical and chemical properties of twin boundaries and related interfaces are described and possible applications are outlined.
In Situ Characterization of Thermo‐Responsive Poly(N‐Isopropylacrylamide) Films with Sum‐Frequency Generation Spectroscopy
Authors: Kurz Volker , Grunze Michael , Koelsch Patrick 
Published: March 2010

AbstractThe thermo‐responsive behaviour of thiol modified poly(N‐isopropylacrylamide) (pNIPAM) films immobilized on gold are probed by in situ broadband sum‐frequency generation (SFG) spectroscopy. The pNIPAM films were prepared by atom transfer radical polymerization (ATRP) using a nitro‐biphenyl‐thiol (NBT)‐SAM on a polycrystalline gold surface as a substrate. Additionally, Raman and infrared reflection absorption spectroscopy (IRRAS) are applied to spin‐coated pNIPAM films. Molecular groups involved in the reorientation and disordering of the polymer chains during the LCST (lower critical solution temperature) transition of pNIPAM are identified. The characteristic vibrations of the CH3 groups show a gradual reorientation of the isopropyl groups within the pNIPAM film and instantaneous reorientation of the outermost CH3 groups around 32 °C.
Synthesis of Dicarbonylruthenium(II) Complexes of Functionalized P,S‐Chelating Diphosphane Ligands and Their Catalytic Transfer Hydrogenation
Authors: Deb Biswajit , Sarmah Podma Pollov , Dutta Dipak Kumar 
Published: March 2010

AbstractThe reaction of P,S‐chelating diphosphane ligands [bis(2‐diphenylphosphanylphenyl)ether monosulfide] (a) and [9,9‐dimethyl‐4,5‐bis(diphenylphosphanyl)xanthene monosulfide] (b) with [Ru(CO)2Cl2]n in a 1:1 molar ratio affords two new ruthenium(II) complexes of the type [Ru(CO)2Cl2(P∩S)] (1a, 1b), where P∩S = a, b. The compounds are characterized by elemental analyses, mass spectrometry, thermal studies, and IR and NMR spectroscopy, together with single‐crystal X‐ray structure determination of bis(2‐diphenylphosphanylphenyl)ether (DPEphos), a, 1a, and 1b. The ruthenium atom in both 1a and 1b occupies the center of a slightly distorted octahedral environment formed by a P atom, an S atom, two Cl atoms, and two CO groups. The crystal structures of a and 1a highlights an interesting feature, in which the P(2)–P(1)–S(1) spatial angle (ca. 174.7°) in free ligand a is reduced to around 46° upon complexation, which indicates a very high flexibility of the angle. Complex 1a also exhibits some hemilabile behavior in solution because of its flexible ligand backbone, while ligand b in complex 1b remains rigid in solution. Complexes 1a and 1b are thermally stable up to about 300 °C and show high catalytic activities in the transfer hydrogenation of aldehydes and ketones to the corresponding alcohols. The highest conversion (about 99 %) with the corresponding TOF value of about 1000 h–1 was obtained for 1a in the case of benzaldehyde. The catalytic efficiency of 1a is found to be much higher than 1b, which might result from the hemilabile behavior of ligand a.
Square‐Planar 2‐Toluenido(triphenylphosphane)nickel(II) Complexes Containing Bidentate N,O Ligands: An Example of Planar Chirality
Authors: Beckmann Udo , Hägele Gerhard , Frank Walter 
Published: March 2010

AbstractNickel(II) complexes comprising electronically delocalised N,O‐chelating ligands are active catalysts in the copolymerisation of carbon monoxide and ethene. Elucidating the mechanism of catalysis presupposes the basic understanding of the intramolecular flexibility of such transition metal complexes. Several nickel(II) complexes with or without planar chirality were synthesised and characterised by NMR spectroscopic techniques and X‐ray diffraction.
Heteroleptic Guanidinate‐ and Amidinate‐Based Complexes of Hafnium as New Precursors for MOCVD of HfO2
Authors: Xu Ke , Milanov Andrian P. , Winter Manuela , Barreca Davide , Gasparotto Alberto , Becker Hans‐Werner , Devi Anjana 
Published: March 2010

AbstractThe synthesis and characterization of four new heteroleptic complexes [Hf{η2‐(iPrN)2CNMe2}2Cl2] (1), [Hf{η2‐(iPrN)2CNMe2}2Me2] (2), [Hf{η2‐(iPrN)2CMe}2Cl2] (3), and [Hf{η2‐(iPrN)2CMe}2Me2] (4) are reported. All the complexes were characterized by spectroscopic methods, while compounds 1–3 were further examined by single‐crystal X‐ray diffraction, revealing that the complexes are monomers with the hafnium center in a distorted octahedral geometry. The thermal properties of the chlorine‐free complexes (2, 4) were examined to determine their suitability for metalorganic chemical vapor deposition (MOCVD) applications, and compound 2 showed good volatility and thermal stability. On the basis of these results, compound 2 was selected for MOCVD of HfO2 with oxygen as oxidant. Depositions were carried out on Si(100) substrates in the temperature range 300–700 °C. The as‐deposited HfO2 films crystallized in the monoclinic phase at temperatures above 500 °C, and the composition analysis determined by Rutherford back‐scattering (RBS) and X‐ray photoelectron spectroscopy (XPS) revealed that the films were stoichiometric and free of carbon. Thus, alkylguanidinatohafnium complex 2 is a promising precursor for growing HfO2 films in a wide temperature range with the desired stoichiometry, because of its adequate volatility, sufficient temperature window between vaporization and decomposition, as well as its ability to decompose cleanly in the presence of oxygen.
Synthesis of Heterocycles by Intramolecular Nucleophilic Substitution at an Electron‐Deficient sp2 Nitrogen Atom
Authors: Sączewski Jarosław , Gdaniec Maria 
Published: March 2010

Abstract2‐Aryl(arylsulfonyl)‐6,7‐dihydro‐2H‐imidazo[2,1‐c][1,2,4]triazol‐3(5H)‐ones and 3‐arylimino‐6,7‐dihydroimidazo[2,1‐c][1,2,4]thiadiazoles have been synthesized by intramolecular nucleophilic substitution reactions at the electron‐deficient sp2 nitrogen atom of 2‐(hydroxyimino)imidazolidine O‐sulfonate. The displacement of the sulfate leaving group by both nitrogen and sulfur anionic nucleophiles proceeds exothermically by in‐plane SN2σ nucleophilic substitution.
Pd‐Promoted Homocoupling Reactions of Unsaturated Silanes in Aqueous Micelles
Authors: Cicco Stefania R. , Farinola Gianluca M. , Martinelli Carmela , Naso Francesco , Tiecco Matteo 
Published: March 2010

AbstractPalladium‐promoted homocoupling reaction of vinyl‐ andpolyenylsilanes in aqueous conditions has been investigated. The reaction is catalyzed by PdCl2 in the presence of the reoxidizing system CuCl2/LiCl and occurs at room temperature in aqueous solutions containing nonionic amphiphiles. Symmetrically α,ω‐disubstituted stereodefined all‐trans polyenes have been obtained in mild conditions and in good yields (65–87 %), higher than those previously reported for the same reactions carried out in methanol or HMPA. A comparison between two commercially available surfactants, Triton X‐100 and PTS, has been performed.
Palladium‐Catalyzed Multialkynyl Cross‐Coupling Reactions with Tetraalkynylindates
Authors: Kang Dongjin , Eom Dahan , Kim Hyunseok , Lee Phil Ho 
Published: March 2010

AbstractAn efficient Pd‐catalyzed multialkynyl cross‐coupling reaction performed with tetraalkynylindates generated in situ from the reaction of 1 equiv. of indium trichloride with 4 equiv. of organometallic reagents has been developed to produce symmetric as well as unsymmetric multialkynyl‐substituted aromatic compounds in good‐to‐excellent yields. In these reactions, the four acetylide groups in the tetraalkynylindates transferred effectively to a variety of aryl bromides.