bluuebunny/crossref_metadata_2025 huggingface dataset:
New approaches to the study of cellulose biosynthesis
Authors: Delmer D. P. , Cooper G. , Alexander D. , Cooper J. , Hayashi T. , Nitsche C. , Thelen M.
Published: May 2013

Examples of a variety of approaches for studying the mechanism and regulation of cellulose biosynthesis are presented. Attempts to demonstrate conclusively a cellulose synthase activity using membrane preparations derived from higher plants have not been successful; the predominant UDP-glucose: β-glucan-β-glucosyltransferase detected in these preparations is a β (1→3)-glucan synthase that is dependent upon Ca2+ and a β-glucobiose, such as laminaribiose or cellobiose, for activity. Xyloglucan glucosyltransferase activity is detected in all plant preparations examined and, in cotton fibres, the activity of this enzyme correlates well with the level of xyloglucan found in the fibre. Low activity for a Mg2+-dependent β-(l→4)-glucan synthase is found in extracts from soybeans and mung beans, but not cotton fibres; this enzyme could represent either a dissociated form of xyloglucan glucosyltransferase or a partially latent form of cellulose synthase. In vitro translation of RNA from developing cotton fibres shows notable increases in the level of several relatively abundant translatable mRNAs associated with the time of onset of secondary-wall cellulose synthesis. In order to determine whether these apparent changes in gene expression represent enhanced expression of specific genes required for cellulose synthesis, several strategies are being developed for identification of specific polypeptides required for this process. One strategy involves the successful development of a technique for detection of glucan synthase activity in acrylamide gels, a technique that should prove useful for characterization of the polypeptide composition of such enzymes. We have also synthesized a photoaffinity analogue of 2,6-dichlorobenzonitrile (DOB), a potent and specific inhibitor of cellulose synthesis. The analogue is also an effective inhibitor in vivo, and upon ultraviolet irradiation of extracts in the presence of the radioactive analogue, we observe a relatively specific labelling of a polypeptide of 18 × 103Mr. Finally, we have studied the spatial regulation and structural requirements for cellulose synthesis in internode cells of the alga Chara corallina. Cellulose deposition in vivo shows spatial localization, which correlates with acid and base bands along the cell. Using internodes perfused with solutions containing UDP-[14C]glucose and subsequently ligated, we were able to demonstrate synthesis of a highly insoluble cell-wall-localized glucan, thus offering hope that Chara can be developed as another useful system for studying the mechanism and regulation of cellulose synthesis.
The conformation of insulin-like growth factors: relationships with insulins
Authors: Dafgård Eva , Bajaj Mona , Honegger Anne Marie , Pitts Jim , Wood Stephen , Blundell Tom
Published: May 2013

The insulin-like growth factors and hystricomorph insulins have been modelled by interactive computer graphics on the assumption that their sequence homology to insulin implies that they will have a similar tertiary structure. These studies suggest that, although the insulin-related molecules can adopt the insulin fold, they are unlikely to form hexamers and if they form dimers they will be of reduced stability. The non-suppressibility of insulin-like growth factors by anti-insulin antibodies is explained in terms of differences of surface residues in the region A8-A10 and B1-B5. Receptor affinity of insulins and insulin-like growth factors for insulin receptors is explicable in terms of a receptor-binding site in the vicinity of B25 Phe on the insulin surface. An equivalent region around B25 Tyr of insulin-like growth factors may be responsible for their binding to type 1 receptors, although binding type 2 receptors must involve a different surface region not shared by insulin.
The role of stromal cells and growth factors in haemopoiesis and modulation of their effects by the src oncogene
Authors: Dexter T. M. , Whetton A. D. , Spooncer E. , Heyworth C. , Simmons P.
Published: May 2013

In the haemopoietic system the mature blood cells have only a finite lifetime. For example, a circulating granulocyte in the peripheral blood has an approximate half-life of 7h (Cartwright, Athens & Wintrobe, 1964; Dancey, Dubelbeiss, Harker & Finch, 1976) whilst the lifetime of an erythrocyte is approximately 120 days (Wickramasinghe & Weatherall, 1982). This constant ‘death’ of mature functional haemopoietic cells means that new blood cells must replace those that are removed. The process of haemopoiesis provides the mature functional blood cells to replace those lost as a consequence of performing their biological functions (e.g. lymphocytes and macrophages in the immune response) or through apparent old age and breakdown (e.g. erythrocytes that are 110-120 days old). The major questions that we are required to answer about this process are ‘where do all these new cells come from?’, ‘what regulates their production?’ and ‘how is this mechanism of control lost in haemopoietic disorders such as leukaemia, hyperproliferative diseases and anaemias?’. Recent work in the field of haemopoiesis has given some clues to the answers to the questions, which provide an intriguing insight into not only haemopoiesis itself but the possible lesions associated with the various blood disorders.
Growth Polarity And Cytokinesis In Fission Yeast: The Role Of The Cytoskeleton
Authors: Marks John , M. Hagan Iain , S. Hyams Jeremy
Published: May 2013

The distribution of F-actin in the fission yeast Schizosaccharomyces pombe was investigated by fluorescence microscopy using rhodamine-conjugated phalloidin. Fluorescence was seen either at the ends of the cell or at the cell equator. End staining was predominantly in the form of dots whilst equatorial actin was resolved as a filamentous band. The different staining patterns showed a close correlation with the known pattern of cell wall deposition through the cell cycle. In small, newly divided cells actin was localized at the single growing cell end whilst initiation of bipolar cell growth was coincident with the appearance of actin at both ends of the cell. As cells ceased to grow and entered cell division, a ring of actin was seen to anticipate the deposition of the septum at cytokinesis. The relationship between actin and cell wall deposition was further confirmed in three temperature-sensitive cell division cycle (cdc) mutants; cdc 10, cdc 11 and cdc 13. Immunofluorescence microscopy of S. pombe with an anti-tubulin antibody revealed a system of cytoplasmic microtubules extending between the cell ends. The function of these was investigated in the coldsensitive, benomyl-resistant mutant benL In cold-grown cells actin was seen to form conspicuous filamentous rings around the nucleus. The origin of these and the possible role of microtubules in the cell-cycle-dependent rearrangements of F-actin are discussed.
Morphogenesis And The Control Of Microtubule Dynamics In Cells
Authors: Kirschner Marc , Schulze Eric
Published: May 2013

Microtubules show unusual dynamic properties at steady state in vitro. While overall the polymer mass remains stable, individual polymers in the population are either growing or shrinking. This phenomenon called dynamic instability is best explained by the known coupling of polymerization to GTP hydrolysis, and the hypothesis that the stability or instability of the whole polymer is determined by whether GTP or GDP is bound to the terminal subunit. Similar unusual dynamics have now also been found in vivo. By visualizing new subunit assembly after injection of tubulin modified with biotin into living fibroblast cells, we can visualize new growth on individual microtubules with antibody to biotin. Microtubules grow in vivo at about 4 µm min-’ and after rapid and precessive depolymerization old microtubules are replaced by new growth from the centrosome. Some microtubules turn over much more slowly and these stable microtubules have a different spatial distribution from the majority of dynamic ones. The existence of both stable and dynamic microtubules in the same cell suggests a model for morphogenesis of the microtubule cytoskeleton. The rapid turnover of microtubules in the cell provides a complex population upon which selective factors can act. Stability can be generated at the end of the polymer and affects the entire microtubule. This model of selective stabilization at the microtubule ends is discussed in terms of recent experiments on the establishment of kinetochore-pole microtubules during mitosis.
Molecular evolution of viruses; ‘trees’, ‘clocks’ and ‘modules’
Authors: Gibbs Adrian
Published: May 2013

Comparisons of the nucleotide sequences of viral genomes, and derived amino acid sequences, mostly confirm the traditional taxonomic groupings of viruses. These comparisons have also shown unexpected homologies between genes of viruses from different groups previously thought to be unrelated, and between some viral and non-viral genes. Comparisons of the three-dimensional structures of the particle proteins of some viruses have also revealed unexpected relationships, and, together with the sequence homologies, suggest that some ancestral viruses had ‘modular’ origins.

Some of the sequence differences have been used to construct phylogenies. However, there is evidence that viral gene ‘molecular clocks’ do not always keep time consistently over very long or very short evolutionary time periods. Clues on evolution mostly come from comparative studies of living or fossil organisms. Fossils of viruses are not known, and thus clues of the origins and evolution of viruses are obtained by comparing extant forms. For example, by comparing isolates of different viruses, or strains of viruses, one can infer the properties of their ancestors, and by comparing isolates obtained during an epidemic, and sequentially related to one another, one can observe directly the type and timing of evolutionary changes.
The TATA-binding protein is a general transcription factor for RNA polymerase III
Authors: White Robert J. , Rigby Peter W. J. , Jackson Stephen P.
Published: May 2013

The TATA-binding protein (TBP) is a principal component of the general factor TFIID and is required for specific transcription by RNA polymerase II. We have shown that TBP is also a general factor for RNA poly-merase III.
Multiple effects on liver-specific gene expression in albino lethal mice caused by deficiency of an enzyme in tyrosine metabolism
Authors: Kelsey Gavin , Ruppert Siegfried , Schedl Andreas , Schmid Erika , Thies Edda , Schütz Günther
Published: May 2013

alf/hsdr-1 is a locus in the mouse defined by albino deletions to be essential for neonatal viability. Homozygous deletion of alf/hsdr-1 leads to a pleiotropic phenotype in liver and kidney, including impaired perinatal activation of hormone-dependent genes, and the induction of detoxifying enzymes and early-response genes. To elucidate the molecular basis of this complex phenotype, we have identified the gene mapping at alf/hsdr-1 by positional cloning, using overlapping albino locus deletions to define the location of alf/hsdr-1. The gene encodes fumarylacetoacetate hydrolase, F AH, an enzyme of tyrosine metabolism. Genetically determined FAH deficiency in man leads to a severe liver failure in infants. In mice, we find that the normal sites of expression of FAH correlate tightly with cell-types which display abnormalities in albino lethal mice. The identification of the Fah gene as a candidate for alf/hsdr-1 offers a novel explanation for the complex phenotype, one into which all aspects can be accommodated. The phenotype can now be understood as a sequence of responses to toxic electrophilic metabolites.
Targets of homeotic gene regulation in Drosophila
Authors: White R. A. H. , Brookman J. J. , Gould A. P. , Meadows L. A. , Shashidhara L. S. , Strutt D. I. , Weaver T. A.
Published: May 2013

We have used a chromatin immunopurification approach to identify target genes regulated by the homeotic gene Ultrabithorax. A monoclonal antibody against the Ultrabithorax gene product is used to immunopurify in vivo Ultrabithorax protein binding sites in embryonic chromatin. The procedure gives an enrichment of sequences with matches to a consensus homeodomain binding site. In one case we have shown that an immunopurifled sequence lies within a 4 kb fragment that acts in vivo as a homeotic response element. We anticipate that this approach will enable us to identify further targets, allowing the analysis of their regulation and function. The chromatin immunopurification strategy may be of general application for the identification of direct in vivo targets of DNA-binding proteins.
The regulation of euchromatin and heterochromatin by histones in yeast
Authors: Grunstein M. , Hecht A. , Fisher-Adams G. , Wan J. , Mann R. K. , Strahl-Bolsinger S. , Laroche T. , Gasser S.
Published: May 2013

Yeast chromosomes may lack the linker histone Hl (normally required to compact 10 nm beads-on-a-string fiber into the 30 nm fiber) and there is no cytological evidence for higher order fiber structure but they do contain regions which correspond to euchromatin and heterochromatin of higher eukaryotes. Both euchromatin and heterochromatin contain nucleosomal particles (composed of two molecules each of histones H2A, H2B, H3 and H4), however histones have been shown to regulate genes in these regions in quite different ways. The mechanisms by which such regulation occurs are the topic of this paper.
Synthesis and Molecular Shuttling of [2]Rotaxanes under Mild Conditions
Authors: Tukada Hideyuki , Hiraki Toshihiro , Nakamura Hiroshi
Published: May 2013

[2]Rotaxanes constructed with an ethereal end-capped axle and a dibenzo-24-crown-8 wheel were synthesized from pseudorotaxanes bearing an alcoholic terminus and diaryldiazomethanes using diphenyl phosphate as a catalyst. The reaction proceeded at room temperature in nonpolar solvents within several hours. The [2]rotaxanes thus obtained behaved as ammonium salts derived from a very strong base such as DBU. Thus, the amine form of the [2]rotaxane reacted with a weak acid, CO2–H2O, to give a hydrogencarbonate salt of the [2]rotaxane, which turned back to the amine form after drying followed by evacuation.
Molecular Design of High-molecular-orientation Electron-transport Materials and Application to Organic Light-emitting Diodes
Authors: Togashi Kazunori , Sagara Yuta , Yasuda Takuma , Adachi Chihaya
Published: May 2013

Two novel electron-transport materials (ETMs), 2,3′-Bpy-TP and 2,4′-Bpy-TP, with high horizontal molecular orientation to substrates, were synthesized. It was shown by measuring the IR absorption spectra of their deposited thin films that C–H···N hydrogen bonds are formed between the 2,3′-Bpy-TP molecules and between the 2,4′-Bpy-TP molecules. It was also shown that there is a closed relationship between their molecular orientations and the driving voltages of electron-only devices (EODs) using them as electron-transport layers (ETLs).
The platelet fibrinogen receptor: from megakaryocyte to the mortuary
Authors: Albert Ferro , Christopher N Floyd
Published: May 2013

Platelets are integral to normal haemostatic function and act to control vascular haemorrhage with the formation of a stable clot. The fibrinogen receptor (glycoprotein IIb/IIIa [GPIIb/IIIa]) is the most abundant platelet integrin and, by binding fibrinogen, facilitates irreversible binding of platelets to the exposed extracellular matrix and enables the cross-linking of adjacent platelets. The vital role of GPIIb/IIIa requires tight control of both its synthesis and function. After transcription from distinct domains on chromosome 17, the two subunits of the heterodimer are carefully directed through organelles with intricate regulatory steps designed to prevent the cellular expression of a dysfunctional receptor. Similarly, exquisite control of platelet activation via bidirectional signalling acts to limit the inappropriate and excessive formation of platelet-mediated thrombus. However, the enormous diversity of genetic mutations in the fibrinogen receptor has resulted in a number of allelic variants becoming established. The Pro33 polymorphism in GPIIIa is associated with increased cardiovascular risk due to a pathological persistence of outside-in signalling once fibrinogen has dissociated from the receptor. The polymorphism has also been associated with the phenomenon of aspirin resistance, although larger epidemiological studies are required to establish this conclusively. A failure of appropriate receptor function due to a diverse range of mutations in both structural and signalling domains, results in the bleeding diathesis Glanzmann's thrombasthaenia. GPIIb/IIIa inhibitors were the first rationally designed anti-platelet drugs and have proven to be a successful therapeutic option in high-risk primary coronary intervention. As our understanding of bidirectional signalling improves, more subtle and directed therapeutic strategies may be developed.
Assessment of Leukocyte Trafficking in Humans using the Cantharidin Blister Model
Authors: Jenner William J , Gilroy Derek W
Published: May 2013

The cantharidin blister model provides an in vivo assessment of the innate inflammatory response in humans. It allows researchers to profile the acute and resolving inflammatory response in healthy and diseased states and for the design of crossover trials for the testing of new treatments for acute inflammation. Below we describe the materials and methods required to prepare, induce, aspirate and analyse the forearm cantharidin blisters, in preparation for future study design.
Bio-repository of DNA in stroke: a study protocol of three ancestral populations
Authors: Cotlarciuc Ioana , Khan Muhammad Saleem , Maheshwari Ankita , Yadav Sunaina , Khan Fahmi Yousif , Al-Hail H , De Silva Ranil , Gorthi S P , Gupta Salil , Sharma Shri Ram , Sylaja P N , Prasad Kameshwar , Sharma Pankaj
Published: May 2013

Stroke is a leading cause of death and disability in the world. Identifying the genes underlying stroke risk may help us to improve our understanding of the mechanisms that cause stroke and also identify novel therapeutic targets. To have sufficient power to disentangle the genetic component of stroke, large-scale highly phenotyped DNA repositories are necessary. The BRAINS (Bio-repository of DNA in stroke) study aims to recruit subjects with all subtypes of stroke as well as controls from UK, India, Sri Lanka and Qatar. BRAINS-UK will include 1500 stroke patients of European ancestry as well as British South Asians. BRAINS-South Asia aims to recruit 3000 stroke subjects and 3000 controls from across India and Sri Lanka. BRAINS-Middle East aims to enrol 1500 stroke patients from Qatar. The controls for BRAINS-Middle East will be recruited from a population-based Qatari Biobank. With the addition of new recruitment centres in India and Qatar, we present an updated version of the BRAINS study protocol. This is the first international DNA biobank for stroke patients and controls from the Middle East. By investigating the influence of genetic factors on stroke risk in European, South Asian and Middle Eastern populations, BRAINS has the potential to improve our understanding of genetic differences between these groups and may lead to new population-specific therapeutic targets.
Platt versus Pickering: what molecular insight to primary hyperaldosteronism tells us about hypertension
Authors: Brown Morris J
Published: May 2013

Recent genomewide analyses have found 50 loci associated with variation in blood pressure but failed to advance understanding of the molecular basis of hypertension. Whether hypertension is not after all due to multiple common variants or is simply an order of magnitude more complex than previously suspected remains unsettled – in part because only a minority of subjects in the analyses had true hypertension. A better starting point than normotensive subjects for explaining hypertension may be the most common distinct cause of hypertension, primary hyperaldosteronism (PHA). The findings that 40% of patients with an aldosterone-producing adenoma (APA) of the adrenal have somatic gain-of-function mutations in a single gene, KCNJ5, and that this gene is, less frequently, mutated in inherited cases of PHA, potentially transform the understanding and management of hypertension. Firstly, they illustrate how hypertension could be due to a multiplicity of uncommon variants. Mutations that present with abnormal electrolytes and anatomy are the easiest to detect but are likely the tip of the iceberg. Secondly, we found a genotype:phenotype pattern, with KCNJ5 mutations inducing larger APAs in the cortisol-secreting zona fasciculata in young women. Smaller APAs without KCNJ5 mutations usually present in older men with resistant hypertension, having been overlooked earlier because of their size. This reflects their compact zona glomerulosa cells. Routine measurement of plasma renin in hypertension and a new positron emission tomography/ computerized tomography allow prompt diagnosis and management of PHA before resistant hypertension ensues. Wider recognition of distinct phenotypes should permit earlier, specific treatment and reduce life-time risk of complications.
Arterial stiffness
Authors: Quinn Ursula , Tomlinson Laurie A , Cockcroft John R
Published: May 2013

Measurements of biomechanical properties of arteries have become an important surrogate outcome used in epidemiological and interventional cardiovascular research. Structural and functional differences of vessels in the arterial tree result in a dampening of pulsatility and smoothing of blood flow as it progresses to capillary level. A loss of arterial elastic properties results a range of linked pathophysiological changes within the circulation including increased pulse pressure, left ventricular hypertrophy, subendocardial ischaemia, vessel endothelial dysfunction and cardiac fibrosis. With increased arterial stiffness, the microvasculature of brain and kidneys are exposed to wider pressure fluctuations and may lead to increased risk of stroke and renal failure. Stiffening of the aorta, as measured by the gold-standard technique of aortic Pulse Wave Velocity (aPWV), is independently associated with adverse cardiovascular outcomes across many different patient groups and in the general population. Therefore, use of aPWV has been proposed for early detection of vascular damage and individual cardiovascular risk evaluation and it seems certain that measurement of arterial stiffness will become increasingly important in future clinical care. In this review we will consider some of the pathophysiological processes that result from arterial stiffening, how it is measured and factors that may drive it as well as potential avenues for therapy. In the face of an ageing population where mortality from atheromatous cardiovascular disease is falling, pathology associated with arterial stiffening will assume ever greater importance. Therefore, understanding these concepts for all clinicians involved in care of patients with cardiovascular disease will become vital.
Crystal structure of bis(2-(3-(carboxylatomethyl-κO,O')-4-(phenylthio)- phenyl)propanoate-κO,O')bis(2,2'-dipyridyl-κN,N')dizinc(II), C54H44N4O8S2Zn2
Authors: Shi Zhan-Wang , Liang Peng , Cen Cui-Ling , Zhao Rong-Ping , Wei Xi , Guan Nian
Published: May 2013

C54H44N4O8S2Zn2, monoclinic, P21/c (no. 14), a = 13.299(4) Å, b = 12.019(3) Å, c = 15.320(4) Å, β = 93.256(4)°, V = 2444.8 Å3, Z = 2, Rgt(F) = 0.0502, wRref(F2) = 0.1430, T = 296 K.
Crystal structure of bis(nitrito-κN)bis(3-phenylpyridine-κN) palladium(II), C22H18N4O4Pd
Authors: Ha Kwang
Published: May 2013

C22H18N4O4Pd, monoclinic, P21/c (no. 14), a = 7.474(1) Å, b = 13.496(2) Å, c = 10.587(2) Å, β = 108.549(4)°, V = 1012.5 Å3, Z = 2, Rgt(F) = 0.0403, wRref(F2) = 0.0794, T = 200 K.
Live subtitling with speech recognition. Causes and consequences of text reduction
Authors: Waes Luuk , Leijten Mariëlle , Remael Aline
Published: May 2013

Speech technology has made it possible to use speech recognition for the simultaneous subtitling of live television broadcasts using the technique of respeaking. Analyses show that live subtitles, like pre-recorded subtitles, are nearly always a reduced form of the spoken comments. However, the live-subtitling process in itself may have an effect on the reduction strategies used by live subtitlers. The aim of this study is to gain a better understanding of the causes and consequences of quantitative text reduction in live subtitling. Three excerpts of an infotainment talk show were subtitled by twelve respeakers of the Flemish public television channel, VRT. They were instructed to complete the task using three different reduction conditions. Various subtitle features, such as reduction percentages and delay, as well as measures of the respeakers’ working memory were collected. In a hierarchical multilevel analysis we defined which external factors affect the degree of reduction. The results show that reduction is not a random process. In contrast, its occurrence and form are largely determined by a number of external factors, viz. delay, amount of source text and the proportion of ‘full’ deletions. A large volume of evidence suggests that respeakers opt to omit certain comments rather than reducing them. It also appears that the decision to delete a comment seems not to be primarily based on the amount of input, while the decision to reduce partially is.
Bridging a grammar gap with explicitation: A case study of the nominalized infinitive
Authors: Južnič Tamara
Published: May 2013

The paper focuses on a textual shift that was observed in a comparison between the Italian nominalized infinitive and its Slovene translations. The nominalized infinitive essentially allows a process to be worded as a nominal structure, while (at least partly) retaining its verbal nature; in the framework of systemic functional grammar, it is explained as a type of grammatical metaphor, i.e. nominalization. The absence of a parallel structure in the grammar of Slovene requires the translator to look for other means of expression. A corpus analysis, carried out with the aid of a parallel corpus which comprises both literary and non-literary Italian texts and their Slovene translations, shows that the dual (nominal and verbal) nature of the nominalized infinitive is reflected in two main types of translation equivalents and several minor ones. It is argued that the strategies displayed in the choice of these translation equivalents can be viewed as instances of obligatory explicitation, either norm-governed or strategic. Thus the main goals of the paper are to identify the textual shifts and strategies found in the parallel corpus and to see whether they can be explained as manifestations of explicitation.
Aesthetic values in literary translation: Zhang’s versus Dong’s version of David Copperfield in Chinese
Authors: Lu Shao
Published: May 2013

The analyses and discussions herein, regarding the Chinese translations of Charles Dickens’sDavid Copperfieldby Zhang Guruo and Dong Qiusi, offer insights into the process of translating that produces aesthetic equivalence. Through an investigation of how Zhang succeeds in representing the source text’s aesthetic values in his target text, I argue that aesthetic values in literary texts need not be restricted either to linguistics or to aesthetics. Therefore, I will focus on the general implications of translation, so that the insights thus gained can be applied to the broader field of literary translation.This paper first examines the general process of representing aesthetic values, which involves three stages: aesthetic comprehension, aesthetic transformation and aesthetic improvement. Second, Zhang’s translation methods and his theoretical thinking concerning translation is compared with Dong’s translation process in an attempt to show that aesthetic equivalence is an important factor in effectively governing literary translation. Third, based on Zhang’s Chinese translation ofDavid Copperfield, in-depth discussions via Zhang’s contrastive techniques intend to show that the process of transforming linguistic meaning and aesthetic images into the target text results in image actualisation. Fourth,simpaticoor’ empathy’ between linguistic meaning and aesthetic experience across languages will be discussed.
Surface Characterization of Clean Gd5Ge4(010)
Authors: Yuen Chad D. , Miller Gordon J. , Thiel Patricia A.
Published: May 2013

Based on X-ray photoelectron spectroscopy, Gd5Ge4(010) does not show evidence of surface segregation. Scanning tunneling microscopy reveals two types of terraces which alternate laterally on the surface. From the step heights, these two surface terminations are assigned as dense, Gd-pure layers in the bulk structure. There is evidence of reconstruction on one type of terrace.
SEMICONDUCTOR BEHAVIOR OF 2, 5-AROMATIC DISUBSTITUTED PYROLLES, AN EXPERIMENTAL AND THEORETICAL STUDY
Authors: Fomina L. , Valdivieso C. Y. León , Galán G. Zaragoza , Bizarro M. , Zaragoza I. P. , Sánchez J. Godínez , Salcedo R. , Baeza A.
Published: May 2013

Theoretical calculations were performed on 2, 5-aromatic substituted pyrroles which have a nitro-benzene or a cyano-benzene link to the nitrogen atom of the pyrrol fragment. The molecules manifested interesting semiconductor behavior that was confirmed when thin films were prepared and their corresponding electrical characterization undertaken. The reason for this behavior is discussed, with reference to the electron withdrawing feature of the substituents in the benzene chain.
Reversible Light-Induced On-Off Switching of Charge Traps in Quantum Dots Probe by Variable-Pulse-Rate Photoluminescence Spectroscopy.
Authors: Aresti Mauro , Marceddu Marco , Saba Michele , Quochi Francesco , Huang Jing , Talapin Dmitri V. , Mura Andrea , Bongiovanni Giovanni
Published: May 2013

We devise an experiment, variable pulse rate photoluminescence, to control the accumulation of charges and the activation of charge traps in colloidal nanocrystals. The dynamics of these states is studied, with pulse repetition frequencies ranging from a few hundred hertz to the megahertz regime, by monitoring photoluminescence spectrograms with picosecond temporal resolution. We find that both photocharging and charge trapping contribute to photoluminescence quenching, and both processes can be reversibly induced by light.
Atomistic Modeling of Alumina/Epoxy Adhesion
Authors: Mackenzie F.O. Valega , Thijsse B. J.
Published: May 2013

In this work we report a specialized reactive force field (ReaxFF) developed for the study of alumina/epoxy interfaces. Force field parameters were obtained by fitting the reactions of small clusters and separate components of epoxies on alumina surfaces in the alpha phase. We also introduce a procedure to obtain crosslinked epoxies based on a proximity criterion to drive reactions and induce crosslinking. Properties of the resulting polymer, like the coefficient of thermal expansion, are found to be of the same order of magnitude as in experiments. Molecular dynamics was used to calculate the adhesion between these polymers and different alumina surfaces: Al2O3-deficient, Al-terminated, O-terminated, 12% and 75% hydroxylated. Typical values for strong adhesion are about 0.70 J/m2 which compare well with previously reported works. The role of defects is also studied.
Plasmonic nanoparticle enhanced and extended performance of Light-sensitive nanocrystal skins
Authors: Akhavan Shahab , Gungor Kivanc , Demir Hilmi Volkan
Published: May 2013

We report on light-sensitive nanocrystal skin (LS-NS) platforms composed of monolayer visible nanocrystals (NCs) on top of bilayers of polyelectrolyte polymers. These LS-NS devices are operated on the principle of photogenerated potential buildup, unlike common photodetectors that operate on the basis of charge collection. The resulting devices are as highly sensitive as common photosensors, despite utilizing a monolayer of NCs and requiring no applied external bias. In this device architecture, using only a single NC monolayer also allows to reduce noise current generation. This LS-NS platform is highly stable under ambient conditions with fully sealed NC monolayer, promising for low-cost large-area UV/visible sensing applications. However, such visible NC based LS-NS devices exhibit limited performance in the long wavelength range due to the low optical absorption of these NCs (e.g., CdTe NCs) in this spectral range. Here, to enhance the device sensitivity, incorporating silver nanoparticles into LS-NS is proposed and demonstrated. For that, the optical absorption of CdTe monolayer NCs in the LS-NS devices is increased using the embedded silver nanostructures. With plasmon coupling, we observe a 2.6-fold enhancement factor in the photosensitivity around the localized surface plasmonic resonance peak of the nanostructures. Higher sensitivity improvement is also obtained at longer wavelengths. To predict the enhancement in the sensitivity of the LS-NS, numerical simulations are performed and the simulation results are found to agree well with the experimental data. Plasmonically enhanced LS-NS hold great promise for large-area photosensing applications extending from UV to IR including windows and facades of smart buildings.
Salt Tolerance of 74 Turfgrass Cultivars in Nutrient Solution Culture
Authors: Friell Joshua , Watkins Eric , Horgan Brian
Published: May 2013

Turfgrass may experience significant salt stress due to poor water quality, insufficient leaching, or exposure to environmental contaminants. Establishment of salt‐tolerant turfgrass cultivars is one possible method of mitigating the effects of salts in irrigation water or the soil environment. The objective of this research was to evaluate the relative salt tolerance of cool‐season turfgrasses in a controlled environment using digital image analysis. Six replications of 74 cool‐season turfgrasses were established using recommended seeding rates in 10.16‐cm by 10.16‐cm pots of silica sand for 12 wk, and suspended in two 760‐L tubs of half‐strength Hoagland solution. Following an adaptation period, all pots were exposed to salinity levels of 4, 14, and 24 dS m−1 successively, each for 2 wk. Digital images were collected after each exposure level using a custom light box, and analyzed for percent green tissue. Cultivars of tall fescue (Festuca arundinacea Schreb.) were found to be most salt tolerant, with ‘Wolfpack II’ and ‘Jaguar 4G’ performing best after the 14 and 24 dS m−1 exposure levels, respectively. Many fine fescue entries performed well, including slender creeping red fescues (Festuca rubra L. ssp. litoralis) ‘Sealink’, ‘Seabreeze GT’, and ‘Shoreline’. Trial entries found to have consistent salt tolerance at all levels may be used to guide recommendations for turfgrass managers and breeders and have potential for use in salt‐tolerant mixtures.
Harvest Timing Affects Switchgrass Production, Forage Nutritive Value, and Nutrient Removal
Authors: Kering Maru K. , Guretzky John A. , Interrante Sindy M. , Butler Twain J. , Biermacher Jon T. , Mosali Jagadeesh
Published: May 2013

Switchgrass (Panicum virgatum L.) has potential for both bioenergy and forage. The objectives of this experiment were to (i) determine whether switchgrass could be harvested for greater nutritive value during the vegetative stage relative to early reproductive growth (boot stage); (ii) compare biomass yields of switchgrass harvested once vs. twice per year for bioenergy; and (iii) examine effects of N fertilizer rates on harvest systems. The experiment was a randomized complete block design with a split‐plot arrangement of harvest system treatments as main plot (harvest once per year after frost, harvest twice per year first at vegetative or boot stage, and regrowth after frost) and N fertilizer rate as subplots (0, 90, 180, and 270 kg N ha−1). Biomass yield was greatest and nutrient concentrations were least in the one‐cut system. For the two‐cut system, nutritive values and yields were similar. Total annual biomass increased linearly with N fertilization. Across N rates, crude protein (CP) concentration for the two‐cut systems was 50% greater (71 g kg−1) and acid detergent fiber (ADF) and neutral detergent fiber (NDF) concentrations were 20% lesser (465 and 856 g kg−1, respectively) than switchgrass in the one‐cut system. –Switchgrass harvested at vegetative through boot stage and its regrowth could provide forage of acceptable nutritive value to beef cows. However, greater nutrient removal requires appropriate soil fertility evaluation and fertilizer management for sustainable yields.
Seed Safening from Herbicidal Injury in Switchgrass Establishment
Authors: Rushing J. Brett , Baldwin Brian S. , Taylor Alan G. , Owens Vance N. , Fike John H. , Moore Ken J.
Published: May 2013

Weed control during the establishment year of switchgrass (Panicum virgatum L.) is critical for a successful stand. Laboratory and field studies were conducted for 2 yr to evaluate the effectiveness of seed safeners for protecting switchgrass seed from the preemergent herbicide metolachlor. Initial evaluations of six seed safeners determined that fluxofenim was the only successful protectant tested for switchgrass seedling germination. Safener rates 0, 25, 50, and 100% of the recommended rate (40 mg a.i. 100 g per seed), method of application (coating vs. controlled hydration), ecotype (lowland vs. upland), dry matter yield, and number of crowns per row were analyzed in replicated field trials conducted in Starkville, MS, Ames, IA, Blacksburg, VA, and Brookings, SD, in a randomized complete block design. Two establishment years were planted in single‐row (6.1 m) plots spaced 50.8 cm apart. Subsequent biomass yield was harvested at the end of each growing season. Exceptional stands were achieved with all rates of safener in both years due to the reduction or elimination of annual grassy weeds and no crop injury was experienced at any test location. The controlled hydration (combination of 25, 50, or 100% fluxofenim) method resulted in significantly greater yields and crown counts than the coating technique at most locations for both years.
Soil Inositol Phosphate Biochemistry: A Call to Link Radiotracer Applications with Spectroscopic Structural Analysis
Authors: L'Annunziata Michael F.
Published: May 2013

Early work on the use of mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy for the structural analysis of soil inositol phosphates and the use of radioisotope tracers to identify and measure soil inositol phosphate transformations is briefly described. Modern advances in the application of MS and NMR to the identification and quantification of soil inositol phosphate stereoisomers including advances in on‐line liquid chromatography (LC) coupled to MS and NMR in hyphenated LC–MS–NMR techniques are reviewed. Automated techniques used to measure 3H, 14C, 33P, and 32P with on‐line LC–NMR and LC–MS are described. Recommendations are made for the use of radioisotope‐labeled myo‐, D‐chiro‐, scyllo‐, and neo‐inositol and their phosphorylated forms in conjunction with the application of modern MS and NMR spectroscopic structural analysis in studies on inositol phosphate transformations in soils.
Removal of phenol from aqueous solution by adsorption onto seashells: equilibrium, kinetic and thermodynamic studies
Authors: Saha Papita Das , Srivastava Jaya , Chowdhury Shamik
Published: May 2013

The efficacy of seashells as a new adsorbent for removal of phenol from aqueous solutions was studied by performing batch equilibrium tests under different operating parameters such as solution pH, adsorbent dose, initial phenol concentration, and temperature. The phenol removal efficiency remained unaffected when the initial pH of the phenol solution was in the range of 3–8. The amount of phenol adsorbed increased with increasing initial phenol concentration while it decreased with increasing temperature. The adsorption equilibrium data showed excellent fit to the Langmuir isotherm model with maximum monolayer adsorption capacity of 175.27 mg g−1 at pH 4.0, initial phenol concentration = 50 mg L−1, adsorbent dose = 2 g and temperature = 293 K. Analysis of kinetic data showed that the adsorption process followed pseudo-second-order kinetics. Activation energy of the adsorption process, calculated using the Arrhenius equation, was found to be 51.38 kJ mol−1, suggesting that adsorption of phenol onto seashells involved chemical ion-exchange. The numerical value of the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) indicated that adsorption of phenol onto seashells was feasible, spontaneous and endothermic under the examined conditions. The study shows that seashells can be used as an economic adsorbent for removal of phenol from aqueous solution.
Treatment of wastewater from a carbon monoxide production unit aimed at water reuse
Authors: Almada R. B. , Fontoura G. A. T. , Bila D. M. , Sant'Anna G. L. , Dezotti M.
Published: May 2013

The industrial wastewater from a carbon monoxide production unit was treated by physico-chemical processes in order to achieve a quality level appropriate for reuse. In preliminary tests, coagulation/flocculation (CF), sand filtration and activated carbon adsorption were investigated in order to select the materials and the process conditions. Based on the results a combined treatment was proposed: CF followed by down-flow filtration in a combined medium (sand and granular activated carbon). The results obtained in a bench-scale treatment unit showed that the combined treatment removed wastewater turbidity (95%), total suspended solids (97%), volatile suspended solids (81%), chemical oxygen demand (74%) and dissolved organic carbon (65%). Polycyclic aromatic hydrocarbons (PAHs) were removed to non-detectable levels. The residual conductivity of the treated wastewater is a matter of concern, and considering the water characteristics of this industrial process, a reuse scheme was proposed based on on-line monitoring and control of conductivity and partial reuse of the treated wastewater.
Do Men who have Sex with Men (MSM) in the United States Understand that HIV Serodiscordance is Possible?
Authors: Wagenaar Bradley H. , Grabbe Kristina L. , Stephenson Rob , Khosropour Christine M. , Sullivan Patrick S.
Published: May 2013

Background

Little is currently known about the extent to which US MSM understand the possibility that a long-term sex partner can have an HIV status different than one’s own status. This information is important in the adaptation of Couples Voluntary HIV Counseling and Testing (CVCT) for US MSM.

Methods

428 US MSM completed an online survey using MySpace.com from March-April, 2009.

Results

Of 426 MSM with complete data, 21.1% (90) were not definitively aware that serodiscordance is possible. Factors associated with a lack of understanding that serodiscordance is possible were: never having tested for HIV (OR: 2.0; CI: 1.1, 3.8), compared to testing 0-6 months previously and having a high school education or less (OR: 2.2; CI: 1.1, 4.5), compared to men who had completed at least some college.

Conclusions

A large proportion of young, internet-using MSM in the United States may not understand that HIV serodiscordance is possible within sexual partnerships. Based on these results, we recommend that CVCT provided to male couples in the United States should include education on HIV serodiscordance.
Effect of body position on indirect measurement of systolic arterial blood pressure in dogs
Authors: Rondeau Danielle A. , Mackalonis Megan E. , Hess Rebecka S.
Published: May 2013

Objective—To determine whether a difference existed in Doppler ultrasonographic measurements of systolic arterial blood pressure (SAP) in sitting versus laterally recumbent dogs and to determine the degree of variability in measurements made in each position.

Design—Diagnostic test evaluation.

Animals—51 healthy or sick adult dogs, without recent sedation or anesthesia and with an SAP ≤ 300 mm Hg.

Procedures—In a crossover design, SAP was measured via Doppler ultrasonography when dogs were sitting (on hind limbs with nonmeasured forelimb bearing weight) and laterally recumbent, with the cuff position at the level of the right atrium for both positions. Seven measurements were obtained per position for each dog.

Results—Mean ± SD SAP was significantly higher in the sitting (172.1 ± 33.3 mm Hg) versus recumbent (147.0 ± 24.6 mm Hg) position, and this difference was evident for 44 of 51 (86%) dogs. The mean difference in measured SAP between the 2 positions was 25.1 ± 28.5 mm Hg. Blood pressure measurements had a significantly higher repeatability in the recumbent position than in the sitting position.

Conclusions and Clinical Relevance—Blood pressure measurements in dogs were significantly affected by body position, and they were higher for most dogs when sitting rather than laterally recumbent. Blood pressure measurements in the laterally recumbent body position were less variable than in the sitting position.
Prevalence of inherited disorders among mixed-breed and purebred dogs: 27,254 cases (1995–2010)
Authors: Bellumori Thomas P. , Famula Thomas R. , Bannasch Danika L. , Belanger Janelle M. , Oberbauer Anita M.
Published: May 2013

Objective—To determine the proportion of mixed-breed and purebred dogs with common genetic disorders.

Design—Case-control study.

Animals—27,254 dogs with an inherited disorder.

Procedures—Electronic medical records were reviewed for 24 genetic disorders: hemangiosarcoma, lymphoma, mast cell tumor, osteosarcoma, aortic stenosis, dilated cardiomyopathy, hypertrophic cardiomyopathy, mitral valve dysplasia, patent ductus arteriosus, ventricular septal defect, hyperadrenocorticism, hypoadrenocorticism, hypothyroidism, elbow dysplasia, hip dysplasia, intervertebral disk disease, patellar luxation, ruptured cranial cruciate ligament, atopy or allergic dermatitis, bloat, cataracts, epilepsy, lens luxation, and portosystemic shunt. For each disorder, healthy controls matched for age, body weight, and sex to each affected dog were identified.

Results—Genetic disorders differed in expression. No differences in expression of 13 genetic disorders were detected between purebred dogs and mixed-breed dogs (ie, hip dysplasia, hypo- and hyperadrenocorticism, cancers, lens luxation, and patellar luxation). Purebred dogs were more likely to have 10 genetic disorders, including dilated cardiomyopathy, elbow dysplasia, cataracts, and hypothyroidism. Mixed-breed dogs had a greater probability of ruptured cranial cruciate ligament.

Conclusions and Clinical Relevance—Prevalence of genetic disorders in both populations was related to the specific disorder. Recently derived breeds or those from similar lineages appeared to be more susceptible to certain disorders that affect all closely related purebred dogs, whereas disorders with equal prevalence in the 2 populations suggested that those disorders represented more ancient mutations that are widely spread through the dog population. Results provided insight on how breeding practices may reduce prevalence of a disorder.