bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological roles of cyclic-nucleotide-gated ion channels in plants: What we know and don’t know about this 20 member ion channel familyThis paper is one of a selection published in a Special Issue comprising papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008.
Authors: Chin Kimberley , Moeder Wolfgang , Yoshioka Keiko
Published: August 2009

Cyclic-nucleotide-gated ion channels (CNGCs) are nonselective cation channels that were first identified in vertebrate retinal photoreceptors and olfactory sensory neurons. The role of CNGCs in animals is well documented, and they are believed to localize to the plasma membrane as heterotetramers. So far, only six CNGC genes (CNGA1–4, CNGB1, and CNGB3) have been identified in mammalian genomes. In contrast, the Arabidopsis thaliana (L.) Heynh. genome encodes 20 putative CNGC subunits that are thought to assemble in the same tetrameric form as animal subunits do. Although the study of Arabidopsis CNGCs is still in its infancy, current research revealed their ability to transport cations that play a role in mediating various biotic and abiotic stresses and developmental processes. This review discusses the current knowledge of plant CNGCs and focuses on functional aspects, with references to heterologous expression studies and reverse genetics analyses. In addition, structural aspects of these channels are discussed.
Auxin-transport-dependent leaf vein formationThis paper is one of a selection published in a Special Issue comprising papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008.
Authors: Donner Tyler J. , Scarpella Enrico
Published: August 2009

The formation of vein patterns in leaves has captivated biologists, mathematicians, and philosophers. In leaf development, files of vein-forming procambial cells emerge from within a seemingly homogeneous subepidermal tissue through the selection of anatomically inconspicuous preprocambial cells. Although the molecular details underlying the orderly formation of veins in the leaf remain elusive, gradually restricted transport paths of the plant signaling molecule auxin have long been implicated in defining sites of vein differentiation. Several recent advances converge to more precisely define the role of auxin flow at successive stages of vascular development. The picture that emerges is that of vein formation as a self-organizing, reiterative, auxin-transport-dependent process.
Overexpression of a directed mutant of 14-3-3ω in Arabidopsis leaves affects phosphorylation and protein content of nitrate reductaseThis paper is one of a selection published in a Special Issue comprising papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008.
Authors: Oh Man-Ho , Huber Joan L. , Shen Wei , Athwal Gurdeep S. , Wu Xia , Huber Steven C.
Published: August 2009

The 14-3-3 family of proteins are highly conserved signaling proteins in eukaryotes that bind to their client proteins, usually through specific phosphorylated target sequences. While the 14-3-3 proteins are thought to interact with a wide array of cellular proteins, there have been few studies addressing the in-vivo role of 14-3-3. As one approach to study this in-vivo role, we generated transgenic Arabidopsis plants constitutively overexpressing a directed mutant of 14-3-3 isoform ω that inhibits phosphorylated nitrate reductase (pNR) in a largely divalent-cation-independent manner in vitro. The transgenic plants had increased relative phosphorylation of NR at the regulatory Ser-534 site and decreased NR activity measured in the presence of 5 mmol·L–1 MgCl2 relative to nontransgenic plants. In addition, total NR protein was increased and the protein half-life was increased about two-fold. Two-dimensional difference gel electrophoresis analysis of proteins extracted from leaves of plants expressing the mutant 14-3-3 identified numerous cellular proteins that were altered in abundance. In particular, several β-glucosidase and glutathione S-transferase isoforms were decreased in abundance relative to wild type plants suggesting a possible alteration in stress or defense responses.
“Genealogy” of plant physiology research in Canada and the founding of the Canadian Society of Plant PhysiologistsThis paper is one of a selection published in a Special Issue comprising papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008.
Authors: Nozzolillo Constance
Published: August 2009

Two men were leaders in the development of plant physiology research in Canada: Professor G.W. Scarth at McGill University and Professor G.H. Duff at the University of Toronto. The latter was the driving force behind the formation of the CSPP in 1958. The contributions of these two men and their graduate students to plant physiology research in Canada are briefly summarized.
Hypobaria, hypoxia, and light affect gas exchange and the CO2compensation and saturation points of lettuce (Lactuca sativa)This paper is one of a selection published in a Special Issue comprising papers presented at the 50th Annual Meeting of the Canadian Society of Plant Physiologists (CSPP) held at the University of Ottawa, Ontario, in June 2008.
Authors: He Chuanjiu , Davies Fred T. , Lacey Ronald E.
Published: August 2009

There are important engineering and crop production advantages in growing plants under hypobaric (reduced atmospheric pressure) conditions for extraterrestrial base or spaceflight environments. The objectives of this research were to determine the influence of hypobaria and reduced partial pressure of oxygen (pO2) (hypoxia) under low and high light irradiance on carbon dioxide (CO2) assimilation (CA), dark-period respiration (DPR), and the CO2compensation and CO2saturation points of lettuce (Lactuca sativa L. ‘Buttercrunch’). Plants were grown under variable total gas pressures [25 and 101 kPa (ambient)] at 6, 12, or 21 kPa pO2(approximately the partial pressure in air at normal pressure). Light irradiance at canopy level of the low-pressure plant growth system (LPPG) was at 240 (low) or 600 (high) µmol·m–2·s–1. While hypobaria (25 kPa) had no effect on CAor the CO2compensation point, it reduced the DPR and the CO2saturation point, and increased the CA / DPR ratio. Hypoxia (6 kPa pO2) and low light reduced CA, DPR, and the CA / DPR ratio. Hypoxia decreased the CO2compensation point regardless of total pressure. Hypoxia also decreased the the CO2saturation point of ambient-pressure plants, but had no effect on hypobaric plants. While low light reduced the CO2saturation point, it increased the CO2compensation point, compared with high-light plants. The results show that hypobaric conditions of 25 kPa do not adversely affect gas exchange compared with ambient-pressure plants, and may be advantageous during hypoxic stress.
Geochemistry, geochronology, and geodynamic setting of Ni–Cu ± PGE mineral prospects hosted by mafic and ultramafic intrusions in the Portneuf–Mauricie Domain, Grenville Province, QuebecGéologie Québec Contribution 8439-2008-2009-5. Geological Survey of Canada Contribution 20080511.
Authors: Sappin A.-A. , Constantin M. , Clark T. , van Breemen O.
Published: August 2009

The Portneuf–Mauricie Domain in the Grenville Province consists of the Montauban group rocks (1.45 Ga), intruded by the La Bostonnais complex plutons (1.40–1.37 Ga). This assemblage was formed in a magmatic arc setting. The sequence was intruded by mafic–ultramafic tholeiitic plutons, some of which host Ni–Cu ± PGE (platinum group element) prospects. U–Pb zircon ages determined from these plutons indicate that the mineralized intrusions were emplaced between 1.40 and 1.39 Ga and that they are coeval with the La Bostonnais complex plutons. The Ni–Cu ± PGE-bearing intrusions have mature island-arc trace element signatures, with strong chemical evidence for differentiation (Mg# and Cr content; MgO and TiO2 contents) and crustal contamination (enrichments in K2O, Rb, Ba, Th, and light rare-earth elements; Th/Yb and Ta/Yb ratios). However, one intrusion displays a back-arc trace element signature associated with evidence for weak crust assimilation. The evolution of the Portneuf–Mauricie Domain is interpreted as follows: (1) 1.45 Ga — Northwesterly directed Andean-type subduction beneath the Laurentian craton margin. Furthermore, northwest-dipping intraoceanic subduction offshore from the continent formed the Montauban island arc. (2) 1.45 to 1.40 Ga — Andean-type subduction led to the formation of a back-arc basin behind the Montauban arc. (3) 1.40 Ga — Emplacement of the La Bostonnais complex plutons, some hosting Ni–Cu ± PGE prospects, into the Montauban arc. (4) 1.39 Ga — Subduction beneath Laurentia led to arc–continent collision and to closure of the back-arc basin. Intrusion of the Ni–Cu ± PGE-bearing plutons ceased. (5) 1.37 Ga — Intrusion of all La Bostonnais complex plutons ceased.
The Late Cambrian (Steptoean; Furongian) trilobite Pseudokingstonia Palmer, 1965 in North America
Authors: Westrop Stephen R. , Adrain Jonathan M.
Published: August 2009

The poorly known Late Cambrian (Steptoean; Furongian) genus Pseudokingstonia Palmer is revised using new material from the type area in west-central Utah. Previously undocumented features of pygidial morphology, including patterns of segmentation of the axis and pleural fields, and articulating flanges on the anterior margin, confirm that the genus is closely related to the dameselloidean Cheilocephalus Berkey and that together they constitute the family Cheilocephalidae Shaw. Pseudokingstonia is diagnosed by a high degree of cranidial and, especially, pygidial effacement, an exceedingly short anterior border on the cranidium, and steeply sloping pygidial borders. In addition to the Great Basin of Nevada and Utah, the genus is also known from Alberta, Arkansas, and Pennsylvania, and all occurrences are confined to the lower half of the late Steptoean Elvinia Zone.
Ecological speciation! Or the lack thereof?This Perspective is based on the author’s J.C. Stevenson Memorial Lecture delivered at the Canadian Conference for Fisheries Research in Halifax, Nova Scotia, January 2008.
Authors: Hendry Andrew P.
Published: August 2009

Ecological speciation occurs when adaptation to different environments or resources causes the evolution of reproductive isolation. This process is now thought to be very important in the evolution of biological diversity. Indeed, support for ecological speciation is so often asserted in the literature that one can get the impression of ubiquity. Eager to ride on the coattails of this exciting work, my own research has investigated ecological speciation in guppies, sticklebacks, and Darwin’s finches. Much to my initial dismay, I failed to find simple and strong signatures of ecological speciation in the first two of these systems. Setting aside the possibility of personal incompetence, my apparent deviation from ubiquity might simply reflect an existing literature bias. This bias seems obvious in retrospect given that essentially all published studies of ecological speciation purport to be confirmatory, whereas many cases of divergent selection and adaptive divergence are associated with only weak to modest levels of reproductive isolation. In short, different populations can be arrayed along a continuum from panmixia to complete reproductive isolation. Variation along this continuum might profitably be used for studying factors, outlined herein, that can promote or constrain “progress” toward ecological speciation.
Shifts between biotic and physical driving forces of species organization under natural disturbance regimes
Authors: Monti Dominique , Legendre Pierre
Published: August 2009

The high ecological values (i.e., the benefits that space, water, minerals, biota, and all other factors that make up natural ecosystems provide to support native life forms) and diversities found in tropical islands emphasize the importance of incorporating disturbance into ecological models. This is of major concern in appreciating how species will survive and adapt to changes and the consequences expected in terms of biodiversity. We predicted that in lotic systems, modification to natural disturbance regimes (fluvial action) would have strong consequences on community organization, with strong disturbance regimes reducing species competitive exclusion through changes in space occupation. We tested this prediction by relating microdistribution data from a crustacean species ( Atya innocous , Decapoda, Atyidae) in small and large rivers in Guadeloupe to two, independently obtained sets of explanatory variables describing the physical environment, as well as the crustacean and fish competitors. Our results show that in rivers with high-energy flow, the driving forces for species coexistence were mostly environmental, whereas in rivers with low-energy flow, biotic interactions were prevalent. These differences linked to natural disturbance regimes revealed that disturbance was a stochastic factor, overlying the classical community-structuring factors and affecting global species relationships.
A combined telemetry – tag return approach to estimate fishing and natural mortality rates of an estuarine fish
Authors: Bacheler Nathan M. , Buckel Jeffrey A. , Hightower Joseph E. , Paramore Lee M. , Pollock Kenneth H.
Published: August 2009

A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum ( Sciaenops ocellatus ) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry – tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ± standard error: 0.04 ± 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry – tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.
Retrospective growth analysis of Atlantic salmon (Salmo salar) from the Miramichi River, Canada
Authors: Friedland Kevin D. , Moore David , Hogan Fiona
Published: August 2009

We have developed a multidecadal retrospective growth history for the principal sea-age groups of the Miramichi River population of Atlantic salmon ( Salmo salar ) that characterizes freshwater growth and marine growth partitioned on a number of different time scales. Based on precedent with European salmon, we tested whether postsmolt growth was positively correlated with recruitment, assuming that growth during the postsmolt year mediates predation mortality. We found no such correlation in the Miramichi postsmolt growth pattern and instead found evidence of a negative correlation between growth and recruitment established by the second month that the fish were at sea. This negative correlation was interpreted as a density-dependant response of the population to recruitment determined early in the marine phase. There was inconsistent evidence that smolt size, as represented by freshwater zone length of the scale, influenced the pattern of recruitment. Finally, we found systematic differences between one-sea-winter (1SW) and 2SW returns related to greater postsmolt growth and, in particular, greater winter growth experienced by fish maturing after the first sea-winter. These data are consistent with findings relating climate variability during the months after smolts migrate to sea and recruitment variability, suggesting that the mortality is a short-duration event independent of growth conditions.
Herbivory by an invasive snail increases nitrogen fixation in a nitrogen-limited stream
Authors: Arango Clay Porter , Riley Leslie Anne , Tank Jennifer Leah , Hall, Robert Ogden
Published: August 2009

Despite anthropogenic nitrogen contributions, nitrogen fixation contributes half of biosphere inputs but has rarely been quantified in streams. Herbivory controls algal biomass and productivity in streams, and we hypothesized that herbivory could also control nitrogen fixation. We released periphyton from herbivory in nitrogen-limited Polecat Creek, Wyoming, where heavy grazing by the invasive New Zealand mudsnail ( Potamopyrgus antipodarum ) dominates nitrogen cycling. One and two weeks after releasing periphyton, we found higher rates of nitrogen fixation on heavily grazed rocks (two-way analysis of variance (ANOVA), p = 0.012). Time elapsed after snail manipulation had no effect (two-way ANOVA, p = 0.24). Grazing changed periphyton composition by reducing the proportion of green algae and increasing the proportion of nitrogen-fixing diatoms (multivariate ANOVA, p = 0.001). Nitrogen fixation rates increased disproportionately to nitrogen-fixing algal cells, indicating that snails increased nitrogenase efficiency, probably by improving light and (or) nutrient availability to nitrogen fixers. We incorporated our nitrogen fixation rates into a published nitrogen budget for Polecat Creek and found that nitrogen flux into the periphyton was 50% higher when we included nitrogen fixation. Herbivory can increase nitrogen fixation in streams, and future studies should measure nitrogen fixation for a more thorough understanding of stream nitrogen cycling.
Genetic structure of the benthic amphipod Diporeia (Amphipoda: Pontoporeiidae) and its relationship to abundance in Lake Superior
Authors: Pilgrim Erik M. , Scharold Jill V. , Darling John A. , Kelly John R.
Published: August 2009

The freshwater amphipod Diporeia is a crucial part of the food web in the Laurentian Great Lakes, but has faced serious declines correlated with the invasion of zebra mussels ( Dreissena polymorpha ), except in Lake Superior, which has seen an increase in Diporeia abundance. Speculation on the mechanisms causing changes in Diporeia densities has not included the possibility of evolutionarily distinct lineages of Diporeia within the Great Lakes. In this study, we use cytochrome c oxidase subunit I (COI) DNA sequence data to investigate the evolutionary history of Lake Superior Diporeia relative to the other Great Lakes and consider potential population structuring within Lake Superior based upon depth or geography. Our analyses reveal that Lake Superior Diporeia represent a distinct lineage that diverged from populations of the other lakes at least several hundred thousand years ago. F statistics show that two localities within Lake Superior were significantly differentiated from all other locales, but analysis of molecular variance did not find significant structure based on depth or geography. Genetic diversity within Lake Superior was not correlated with depth, although abundance was significantly negatively correlated with increasing depth.
Patterns in habitat and fish assemblages within Great Lakes coastal wetlands and implications for sampling design
Authors: Trebitz Anett S. , Brazner John C. , Pearson Mark S. , Peterson Gregory S. , Tanner Danny K. , Taylor Debra L.
Published: August 2009

Discerning fish–habitat associations at a variety of spatial scales is relevant to evaluating biotic conditions and stressor responses in Great Lakes coastal wetlands. Ordination analyses identified strong, geographically organized associations among anthropogenic stressors and water clarity, vegetation structure, and fish composition at both whole-wetland and within-wetland spatial scales. Lacustrine-protected wetlands were generally internally homogeneous in fish composition, whereas riverine or barrier-beach lagoon wetlands could be more heterogeneous, especially if they had large tributaries and complex morphology or if the mouth area was more directly exposed to the adjacent lake than were other areas. A tendency towards more turbidity-tolerant fish but fewer vegetation spawners, nest guarders, or game and panfish differentiated both more-disturbed from less-disturbed wetlands and open-water from vegetated areas within wetlands. Variation in vegetation structure related to wetland hydromorphology and anthropogenic impacts makes standardizing fish sampling protocols by microhabitat impractical across broad spatial or disturbance gradients. We recommend distributing sampling effort across available microhabitats and show that both fish and habitat can be adequately characterized with a single field day of effort.
Semi-empirical model for the prediction of modulus of elasticity for unsaturated soils
Authors: Oh Won Taek , Vanapalli Sai K. , Puppala Anand J.
Published: August 2009

A semi-empirical model is proposed in this paper to predict the variation of modulus of elasticity with respect to matric suction for unsaturated sandy soils using the soil-water characteristic curve (SWCC) and the modulus of elasticity under saturated conditions. Using this model, comparisons are provided between the predicted and measured moduli of elasticity and elastic settlements from model footing test results on three different sandy soils. The results of this study are encouraging as there is good agreement between the predicted and measured moduli of elasticity and settlements.
Evaluating shear mobilization in rockfill columns used for riverbank stabilization
Authors: Alfaro Marolo C. , Blatz James A. , Abdulrazaq Wisam F. , Kim Chang-Seok
Published: August 2009

The major rivers within the City of Winnipeg are founded in glacial Lake Agassiz clay and silt sediments that have low shear strength. As such, riverbank instabilities are a common issue along many stretches of the rivers. The use of rockfill columns has become an increasingly utilized approach for stabilizing failing banks. Recent cases in Winnipeg have shown that movements can occur following installation of rockfill columns. Uncertainty regarding the magnitude of these movements that is required to mobilize shearing resistance in the rockfill columns has resulted in situations where the stability of riverbanks following remediation has been questioned. This has provided a need to improve our understanding about how much movement a stabilized slope must undergo before sufficient shear resistance of the rockfill column will be mobilized. The results of experimental testing conducted to assess the shear mobilization of rockfill column materials using a large-scale direct shear test apparatus are presented in this paper. The testing methodology is described along with the test results. The results show that the development of material specifications, construction, and placement methods and appropriate methods of analysis requires understanding of the stress–strain properties of the in situ soil and the rockfill material.
Seismic bearing capacity of a strip footing on rock slopes
Authors: Yang Xiao-Li
Published: August 2009

Most of the seismic calculations currently used for the evaluation of seismic bearing capacity are formulated in terms of a linear Mohr–Coulomb failure criterion. However, experimental evidence shows that a nonlinear failure criterion is able to represent fairly well the failure of almost all types of rocks. In this paper, a nonlinear Hoek–Brown failure criterion is used to estimate the seismic bearing capacity factor of a strip footing on rock slopes in a limit analysis framework. Quasi-static representation of earthquake effects using a seismic coefficient is adopted for the seismic bearing capacity calculations. A linear Mohr–Coulomb failure criterion, tangent to the nonlinear Hoek–Brown failure criterion, is used to derive the objective function that is to be minimized. Upper-bound solutions are obtained by optimization. For static problems, bearing capacity factors related to uniaxial compressive strength, Nσ, are compared. For seismic problems, Nσfactors for different ground inclinations are presented for practical use in rock engineering.
Model for predicting displacement-dependent lateral earth pressure
Authors: Mei Guoxiong , Chen Qiming , Song Linhui
Published: August 2009

A model for predicting displacement-dependent lateral earth pressure was proposed based on an earth pressure – displacement relationship commonly observed in practice. The proposed model is a monotonically increasing and bounded function, with an inflection point at the displacement of s = 0 at which the earth pressure changes from the intermediate active state (the state between active and at-rest) to the intermediate passive state (the state between at-rest and passive). The proposed model can predict the relationship between earth pressure and retaining structure movement for any condition intermediate to the active and passive states, which was verified by the experimental data reported in published literature. The predicted lateral earth pressure coefficients are in good agreement with the test results of model tests reported in the literature.
A test of various computational solvation models on a set of “difficult” organic compounds
Authors: Guthrie J. Peter , Povar Igor
Published: August 2009

Various dielectric continuum models in Gaussian 03, based on the SCRF approach, PCM, CPCM, DPCM, IEFPCM, IPCM, and SCIPCM, have been tested on a set of 54 highly polar, generally polyfunctional compounds for which experimental solvation energies are available. These compounds span a range of 13 kcal/mol in ΔGt. The root-mean-square (RMS) errors for the full set of compounds range from 2.48 for DPCM to 1.77 for IPCM. For each method, classes of compounds which were not handled well could be identified. If these classes of compounds were omitted, the performance improved, and ranged from 1.58 (PCM, 39 compounds) to 1.02 (IPCM, 42 compounds). Models in the PCM family (PCM, CPCM, DPCM, and IEFPCM) with the recommended UAHF or UAKS sets of radii rely on a highly parameterized definition of the solvent cavity. Where this parameterization was inadequate, the calculated solvation energies were less reliable. This has been demonstrated by devising a new parameterization for PCM and halogen compounds, which markedly improves performance for polyhalogen compounds. The effective radius for the portion of the cavity centered on a halogen atom was assumed to be linear in the electron-withdrawing or -donating properties of the rest of the molecule as measured by Hammett σ (for halogens on aromatic rings) or Taft σ* (for halogens on aliphatic carbons). This new parameterization for PCM was tested on a set of 45 aliphatic and 22 aromatic polyhalogen compounds and shown to do well. IPCM, which was already the best of the methods in Gaussian, can be considerably improved by a parameterization to allow for cavitation, dispersion, and hydrogen bonding. A large set of compounds was used for the parameterization to have multiple examples for each parameter and as far as possible to have molecules with multiple instances of each structural feature. In the end, 15 parameters were found to be defined by the data for 241 compounds. With this parameter set, the RMS error for the set used for fitting was 0.81 kcal/mol, and the RMS error for the original set of 54 compounds was 0.85. With this new parameterization, IPCM is clearly the best of the methods available in Gaussian 03.
Rearrangement mechanisms for azoxypyridines and azoxypyridineN-oxides in the 100% H2SO4region — The Wallach rearrangement story comes full circle
Authors: Buncel Erwin , Keum Sam-Rok , Rajagopal Srinivasan , Cox Robin A.
Published: August 2009

Kinetic studies of the Wallach rearrangements of four azoxypyridines, four azoxypyridine N-oxides, and one azoxypyridine N-methiodide have been carried out in the 100% H2SO4acidity region. For all of the β-isomers in the study the reactions proceeded at a spectrally measurable rate, and the log observed rate constants were found to be linear functions of the log H3SO4+concentration, as previously found for azoxybenzene itself, suggesting that the reaction mechanism for these substrates is the same as that previously deduced for axozybenzene, i.e., a general-acid-catalysis A-SE2 process. For the α-azoxypyridines no reaction could be observed at all. The two α-azoxypyridine N-oxides in the study did react, albeit very slowly, but for these two compounds the log observed rate constants were not linear functions of the log H3SO4+concentration, but were instead found to be linear in the H0acidity function, which is known for the 100% H2SO4acidity region. It follows that the reaction mechanism for these α-isomers is a different one, presumably an A1 process. This mechanism was proposed back in 1963 for azoxybenzene, but has never actually been observed for any substrate before the work reported in this study. Thus, the Wallach rearrangement story can be said to have come full circle.
Hafnium–phosphinimide complexes
Authors: Alhomaidan Osamah , Welch Gregory C. , Bai Guangcai , Stephan Douglas W.
Published: August 2009

A series of phosphinimide complexes of Hf are prepared and characterized. Reaction of the phosphinimine t-Bu3PNH with Hf(NEt2)4 gave (t-Bu3PN)Hf(NEt2)3 (1) but this species was not readily converted to the corresponding HfCl3-derivative. The reaction of 2 equiv. of t-Bu3PNH with Hf(NEt2)4, however, gave (t-Bu3PN)2Hf(NEt2)2 (2), which was readily converted to (t-Bu3PN)2HfCl2 (3) and (t-Bu3PN)2HfMe2 (4). Employing t-Bu3PNLi and HfCl4 afforded (t-Bu3PN)3HfCl (5) while reaction with CpHfCl3 gave rise to ligand redistribution reactions affording (t-Bu3PN)2HfCl2 and Cp2HfCl2. However, Cp(t-Bu3PN)2HfCl (7) was prepared by treating (t-Bu3PN)2HfCl2 with CpNa. The related species of Cp2(t-Bu3PN)HfCl (8) was synthesized by the reaction of Cp2HfCl2 and t-Bu3PNLi. Ligand redistribution was avoided in the reaction of Cp*HfCl3 as Cp*(t-Bu3PN)HfCl2 (9) and Cp*(i-Pr3PN)HfCl2 (10) were readily obtained and derivatized as Cp*(t-Bu3PN)Hf(NMe2)2 (11) and Cp*(t-Bu3PN)HfMe2 (12), respectively. Similarly, ((Me3Si)2C5H3)(t-Bu3PN)HfCl2 (13) was converted to ((Me3Si)2C5H3)(t-Bu3PN)HfMe2 (14). Reactions with Lewis acid activators were used to prepare Cp*(t-Bu3PN)HfMe(THF)MeB(C6F5)3 (15), (Cp*(t-Bu3PN)HfMe)(B(C6F5)4) (16), and (t-Bu3PN)2Hf(H2B(C6F5)2)2 (17). Preliminary testing of 3, 9, and 13 in ethylene polymerization is reported. Compounds 3, 4, 7, 9, and 17 are characterized crystallographically.
Design, chemical synthesis, and in vitro biological evaluation of simplified estradiol–adenosine hybrids as inhibitors of 17β-hydroxysteroid dehydrogenase type 1
Authors: Bérubé Marie , Poirier Donald
Published: August 2009

A series of estradiol (E2) derivatives were designed to interact with both the substrate- and the cofactor-binding sites of 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1). These analogues of potent E2–adenosine hybrid inhibitor EM-1745, where the adenosine moiety was replaced by a more stable benzene derivative, were synthesized from estrone using alkene cross-metathesis and Sonogashira coupling reactions as key steps. In vitro biological evaluation of these steroid derivatives revealed that a spacer of 13 methylenes, between the 16β-position of E2and the adenosine mimic bearing a carboxylic acid group, gave the best inhibition of 17β-HSD1.
Synthesis of both isomers of aziridine derived from the mixture of cis- and trans-limonene oxide
Authors: Mehrabi Hossein
Published: August 2009

A short and efficient route is described for both isomers of aziridine derived from the commercially available 1:1 mixture of limonene oxides. The process is amenable to scale-up and allows easy access to multigram quantities of these useful chiral building blocks.
INDUCED ELECTROMAGNETIC FIELDS IN NONLINEAR QED
Authors: DOMINGUEZ C. A. , FALOMIR H. , IPINZA M. , LOEWE M. , ROJAS J. C.
Published: August 2009

The Euler–Heisenberg effective Lagrangian is used to obtain general expressions for electric and magnetic fields induced by nonlinearity, to leading order in the nonlinear expansion parameter, and for quasistatic situations. These expressions are then used to compute the induced electromagnetic fields due to a spherical shell with uniform charge distribution on the surface, in the presence of an external constant magnetic field. The induced electric field contains several multipole terms with unusual angular dependences. Most importantly, the leading term of the induced magnetic field is due to an induced magnetic dipole moment.
DIRECTIONAL DETECTION OF DARK MATTER
Authors: SCIOLLA GABRIELLA
Published: August 2009

Direct detection of WIMPs is key to understand the origin and composition of Dark Matter. Among the many experimental techniques available, those providing directional information have the potential of yielding an unambiguous observation of WIMPs even in the presence of insidious backgrounds. A measurement of the distribution of arrival direction of WIMPs can also discriminate between Galactic Dark Matter halo models. Here, we will discuss the motivation for directional detectors and review the experimental techniques used by the various experiments. We will then describe the DMTPC detector in more detail.
PHASE TRANSITIONS WITH THE LINE TENSION EFFECT: THE SUPER-QUADRATIC CASE
Authors: PALATUCCI GIAMPIERO
Published: August 2009

Let Ω be an open bounded set of ℝ3 and let W and V be two non-negative continuous functions vanishing at α, β and α', β', respectively. We analyze the asymptotic behavior as ε → 0, in terms of Γ-convergence, of the following functional: [Formula: see text] where u is a scalar density function and Tu denotes its trace on ∂Ω. We show that the singular limit of the energies Fε leads to a coupled problem of bulk and surface phase transitions.
A MATHEMATICAL MODEL FOR CASE HARDENING OF STEEL
Authors: FASANO ANTONIO , HÖMBERG DIETMAR , PANIZZI LUCIA
Published: August 2009

A mathematical model for the case hardening of steel is presented. Carbon is dissolved in the surface layer of a low-carbon steel part at a temperature sufficient to render the steel austenitic, followed by quenching to form a martensitic microstructure. The model consists of a nonlinear evolution equation for the temperature, coupled with a nonlinear evolution equation for the carbon concentration, both coupled with two ordinary differential equations to describe the evolution of phase fractions. We investigate questions of existence and uniqueness of a solution and finally present some numerical simulations.
A MODEL AT THE MACROSCOPIC SCALE OF PROSTATE TUMOR GROWTH UNDER INTERMITTENT ANDROGEN SUPPRESSION
Authors: TAO YOUSHAN , GUO QIAN , AIHARA KAZUYUKI
Published: August 2009

The relapse of tumor is a crucial problem in hormonal therapy of prostate cancer. The so-called androgen-independent cells are considered to be responsible for such a recurrence. These cells are not sensitive to androgen suppression but rather apt to proliferate even in an androgen-poor environment. Bruchovsky et al. in their experimental and clinical studies suggested that intermittent androgen suppression may delay or prevent the relapse when compared with continuous androgen suppression. This paper proposes a model at the macroscopic scale of prostate tumor growth under intermittent androgen suppression. Qualitative analysis shows that the tumor relapse cannot be avoided under continuous androgen suppression for typical parameter values. Numerical simulation supports the above-mentioned experimental and clinical suggestion, and implies an optimal medication scheme of intermittent androgen suppression therapy.
Synthesis of multi-porphyrin dendrimer as artificial light-harvesting antennae
Authors: Jang Woo-Dong , Lee Chi-Hwa , Choi Myung-Seok , Osada Makiko
Published: August 2009

To mimic bacterial light-harvesting antenna complexes, a series of dendritic multiporphyrin arrays, n PZn-PFB (n = 2, 4; cone-shaped dendrimers, n = 8, 16; star-shaped dendrimers), were synthesized and characterized by 1H NMR and MALDI-TOF-MS spectroscopy. Photoinduced energy-transfer efficiency (ΦET) from peripheral Zn porphyrin ( PZn ) units to an inner core free-base porphyrin ( PFB ) in the dendrimers was evaluated by fluorescence measurement. Both star- and cone-shaped multi-porphyrin arrays exhibited significantly high efficiency energy transfer from the photoexcited PZn units to the energy-accepting PFB , where the star-shaped dendrimers, 8PZn-PFB (94%) and 16PZn-PFB (88%), had a slightly higher efficiency than those of the cone-shaped dendrimers, 2PZn-PFB (92%) and 4PZn-PFB (80%), respectively.
The first tin(IV) porphyrin complex with chiral amino acid ligands: synthesis, characterization and X-ray crystal structure of trans-bis(L-prolinato)[5,10,15,20-tetrakis-(4-pyridyl)porphyrinato]tin(IV)
Authors: Kim Soo Hyun , Kim Hyunuk , Kim Kimoon , Kim Hee-Joon
Published: August 2009

The tin(IV) porphyrin complex with chiral amino acid ligands trans-bis(L-prolinato)[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV) (1) was synthesized and fully characterized. The X-ray crystal structural analysis of 1 reveals that the Sn(IV) center is octahedrally coordinated by the porphyrin occupying the square base and axial coordination of two L-prolinate ligands in trans-position with respect to each other. The pyrrolidine rings of the L-prolinate ligands in 1 exhibit a Cs-Cβ -exo envelope conformation with Cs symmetry. The non-classical hydrogen bonding interactions mainly contribute to assemble 1 into a one-dimensional packed structure.
Synthesis and optical properties of tetrapyrazino-porphyrazines containing camphorquinone group
Authors: Jang Chun Keun , Byun Seung Hwan , Kim Song Hak , Lee Do Kyung , Jaung Jae Yun
Published: August 2009

2,3-dicyanopyrazine and metallophthalocyanines were synthesized with magnesium containing (±)camphorquinone substituent. 2,3-dicyanopyrazine was prepared by condensation reaction of diaminomaleonitrile (DAMN) with 1,7,7-trimethylbicyclo[2.2.1]heptane-2,3-dione (1). The tetrapyrazinoporphyrazine was characterized by a combination of UV-visible spectroscopy, fluorescence spectroscopy, infrared radiation, elemental analysis, MALDI-TOF-MS and 1H NMR spectroscopy.
Synthesis and photodynamic activity of new imidazole substituted pyropheophorbide-a derivatives
Authors: Sengee Gerelt-Ireedui , Badraa Narangerel , Shim Young Key
Published: August 2009

Two new imidazole substituted chlorin derivatives, namely (4-[1-imidazolyl]-phenyl)-amide pyropheophorbide-a and (3-[1-imidazolyl]-propyl)-amide pyropheophorbide-a have been synthesized. Their cell viabilities on A549 human lung adenocarcinoma cells were investigated and compared with that of pyropheophorbide-a. According to the phototoxicity study, (4-[1-imidazolyl]-phenyl)-amide pyropheophorbide-a and (3-[1-imidazolyl]-propyl)-amide pyropheophorbide-a were found superior to pyropheophorbide-a with respect to high phototoxicity. This work demonstrates that imidazole substituted chlorin derivatives could be a promising candidate for photodynamic therapy and are worth further investigations.
Self-assembly layer-by-layer fabrication using porphyrin dye anion and polycation
Authors: Kim Byung-Soon , Son Young-A
Published: August 2009

In this study, self-assembled alternating film using poly(diallyldimethylammonium chloride) (PDDAC) and meso-tetrakis(4-carboxyphenyl)porphyrin (MTCP) was prepared as a multilayer deposition on glass substrate. This preparation technique for dye deposition may provide new feasibilities to achieve the manufacture of ultrathin films for nanotechnology application. The deposition films were characterized by UV-vis spectrophotometer and Atomic Force Microscopy (AFM) analysis. The results of UV-vis spectra showed that the absorbance characteristic of the multilayer films linearly increased with an increased number of PDDAC and MTCP bilayers. AFM analysis showed the film surface was relatively uniform and the progressive growth of layers was determined.
Synthesis and characterization of Cu-phthalocyanine hybrid TiO2 sol
Authors: Jang Byeong Uk , Choi Jae Hong , Lee Sung Jun , Lee Se Geun
Published: August 2009

TiO2 sol was prepared by a sol-gel method. Sodium polymethacrylate (PMAA) was added to TiO2 sol, resulting in a stable TiO2-PMAA . The copper(II) phthalocyanine tetrasulfonate ( CuPcTs ) was used to sensitize nanocrystalline TiO2 photocatalyst. The hybrid nanoparticles had an average particle size of 35 nm and core-shell type morphology was observed using a TEM. For the preparation of TiO2-CuPcTs , TiO2 was directly complexed with CuPcTs , leading to a particle size of 100 nm by a sonication treatment. The photodegradation of the hybrid type photosensitizer was measured using AO7 as an indicator with He-Ne laser with wavelength 633 nm. The efficiency of singlet oxygen generation was also measured by the reduction ratio of concentration of trans-1-(2′-methoxyvinyl) pyrene (MVP) responding to the change of fluorescene emission at 420 nm, depending on the irradiation time.
Regulation of intracellular Ca2+ in the cytotoxic response to photodynamic therapy with a chlorin-based photosensitizer
Authors: Yoo Je-Ok , Lee Chang-Hee , Hwang Byeong-Moon , Kim Woo Jin , Kim Young-Myeong , Ha Kwon-Soo
Published: August 2009

We investigated regulation of intracellular Ca2+ induced by photodynamic therapy (PDT) with a new chlorin-based photosensitizer, DH-II-24, in human gastric adenocarcinoma cells. DH-II-24-mediated PDT induced necrotic cell death according to post-irradiation time, and produced intracellular reactive oxygen species (ROS) in an irradiation time-dependent manner. PDT also increased intracellular Ca2+ , and this Ca2+ elevation was largely inhibited by BAPTA-AM but not by EGTA. BAPTA-AM inhibited the ROS production by PDT, whereas NAC and Trolox had no effect on the PDT-induced Ca2+ response. In the presence of EGTA, pre-incubation with thapsigargin, Gly-Phe-β-naphthylamide or brefeldin A had no significant effect on the PDT-induced elevation in intracellular Ca2+ . However, ruthenium red affected the initial and late Ca2+ responses to PDT. Thus, DH-II-24-mediated PDT produces intracellular ROS via elevation in intracellular Ca2+ , contributed, at least in part, by mitochondria, which results in necrotic death of the human gastric adenocarcinoma cells.
Photodynamic inactivation of wound-associated bacteria with new troponyl (pyro)pheophobides
Authors: Bayarmaa Bold , Bayarmaa Barkhuu , Shim Young Key
Published: August 2009

In this study, the effect of light activated agent, methyl (pyro)pheophorbide-a, which bears non-aromatic cyclic compound, excited with red light from a LED on the viability of S. aureus, S. epidermidis, and E. coli was investigated. All species were susceptible to killing by photosensitization and photodynamic effect was dependent on both the chemical structure and concentration. However, E. coli was not susceptible to concentrations used to obtain a significant kill with the Gram-positive bacteria upon irradiation. To more closely mimic the conditions of wounds, photodynamic therapy was carried out on S. aureus, which is the most important organism that can cause a range of mild to severe infections in skin and burn wounds, in the presence of human blood plasma and human serum albumin, representing a wound fluid model. Results indicate that microorganisms could be successfully photoinactivated by tropolone methyl (pyro)pheophorbide-a derivatives when suspended in phosphate buffered saline. However, changing the medium into 4.5% and 7% HSA/PBS solutions reduced the effectiveness of lethal photosensitization of bacteria. The same results were obtained with human blood plasma. Also, the mechanism of bacterial cell inactivation by a sensitizer and light was studied with reactive oxygen species scavengers. Further evidence of the involvement of singlet oxygen is provided by the protective effect of the singlet oxygen scavenger, sodium azide.
The hydration and alteration of perlite and rhyolite
Authors: Denton J.S. , Tuffen H. , Gilbert J.S. , Odling N.
Published: August 2009

The volatile concentrations and thermal characteristics of hydrothermally altered rhyolitic deposits erupted under Icelandic glaciers have been studied by combined differential scanning calorimetry–thermogravimetric analysis–mass spectrometry (DSC–TGA–MS) and X-ray diffraction (XRD). Samples range from pristine obsidians to strongly perlitized and altered fragmental deposits. Four types of samples are determined to have notable differences in total volatile concentrations: obsidians (0.44–3.04 wt%), perlites (2.15–8.15 wt%), obsidian-breccias (8.49–9.41 wt%) and hyaloclastites (3.23–7.78 wt%). DSC–TGA–MS and textural data indicate that the volatile concentration of the perlitic samples increases as the amount of perlitization increases. XRD data show that the volatile-rich samples are rich in the low-temperature zeolite minerals heulandite and mordenite. The temperature at which volatile exsolution occurs is shown to decrease as the volatile concentration increases, reflecting the speciation of water as well as zeolite mineral growth.

Supplementary material:

Detailed grain-size fraction analysis data in table and histogram form are available athttp://www.geolsoc.org.uk/SUP18366.
Evolution and chronology of the Pangong Metamorphic Complex adjacent to the Karakoram Fault, Ladakh: constraints from thermobarometry, metamorphic modelling and U–Pb geochronology
Authors: Streule M.J. , Phillips R.J. , Searle M.P. , Waters D.J. , Horstwood M.S.A.
Published: August 2009

Sillimanite- and staurolite-grade metamorphic rocks exhumed along the Pangong fault, the NE branch of the right-lateral Karakoram strike-slip fault in northern Ladakh, NW India, show multiple episodes of metamorphism and fabric development. Debate has centred on whether these metamorphic rocks were formed as a result of shear heating during strike-slip faulting, or whether they are exhumed earlier metamorphic rocks unrelated to movement on the Karakoram fault. Here we constrain the burial and exhumation history of the Pangong Metamorphic Complex combining the pressure–temperature evolution with accessory phase geochronology. Sillimanite-grade metamorphism in graphitic pelites was superseded by the preserved
P
–
T
conditions of a Bt + Ms + St + Grt + Qtz + Fsp assemblage at 585–605 °C and 6.05–7.25 kbar, equivalent to
c
. 20–25 km of burial. Laser ablation monazite U–Pb geochronology reveals that sillimanite-grade metamorphism occurred at 108.0 ± 0.6 Ma in rocks immediately adjacent to the Pangong strand of the Karakoram fault, implying that most metamorphic rocks along the Karakoram fault were not formed by shear heating during Miocene strike-slip faulting. This age correlates closely with the ages of the Hunza granite–granodiorite batholith, and the K2 orthogneiss in northern Pakistan, and confirms that some high-grade metamorphism occurred before collision and accretion of the Kohistan arc and the Indian plate to Asia; protracted high-grade metamorphism, and accompanying crustal thickening lasted at least 100 Ma along the South Asian plate margin. Our
P
–
T
and geochronology results also demonstrate the continuity of Cretaceous metamorphism across the Karakoram fault.